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Water the building can rely on.

Name: Definitive Water Technologies Johannesburg
Address: Unit 067, Inospace Allandale Exchange, 917 Morkels Close, Halfway House, Midrand, Gauteng, 1685, ZA
Telephone: +27 75 084 5743

CTCape Town+27 21 851 0133 JHBJohannesburg+27 75 084 5743 WhatsApp JHBJohannesburg

Start here: what are you dealing with?

Estates and body corporates, hotels and lodges, offices and schools: you are responsible for the water without being the person who designed or installed the system. Choose what you are dealing with; the three steps below change to match it, and the sections further down cover looking after what is already there.

Keeping water available through interruptions

In one line: size the storage for the hours you actually have to cover, keep the tank sealed, opaque and clean, protect the municipal connection, and treat the water leaving the tank rather than trusting what went into it.

Storage buys you time, and that is all it buys you. A tank keeps the taps running through an interruption, but the day it is installed the building acquires a warm, dark vessel that the municipal chlorine residual fades inside, and a connection back to the municipal main that has to be protected so nothing can flow the wrong way. Both are ordinary, solved problems. Neither solves itself.

What is usually wrong

Match what people in the building are reporting to what is actually happening, and to the stage that deals with it.

What you seeWhat is happeningThe fix

The supply goes off and the building stops with it: No storage, or storage sized on a guess. Work from the hours you must cover and what the building actually uses in those hours, not from the size of the tank the supplier had available.; Storage, pumps and the protected connection
Water from the tanks tastes stale or smells: The chlorine that protected it in the main fades in a warm tank, and biology restarts. Keep the tank sealed, dark and turning over, and treat the water on the way out.; UV disinfection
Brown water for a day after the supply comes back: Repressurising the main scours rust and sediment off old pipework, and the building's own tanks stir up whatever settled. A sediment stage at the point of entry catches it instead of the residents.; Sediment filtration at the point of entry
Pressure falls away on the top floor when the building runs on tanks: The booster set is sized for the tank outlet rather than for the height and the simultaneous demand. This is a pump and pipework question before it is a treatment question.; Storage, pumps and the protected connection
The municipality has asked about the tank connection: Stored or alternative water must not be able to flow back into the municipal main. Backflow prevention is a plumbing requirement, and what specifically is required where you are is set locally — ask your municipality and use a registered plumber.; Storage, pumps and the protected connection

What to test, and what the numbers mean

One laboratory analysis, plus a few readings you can take yourself, tells you which of these apply. These are the lines to read first for this situation, with what each one means for the different things the building uses water for.

Read these first for this situation
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
E. coli and coliforms	Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.	SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.	The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.	Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Free chlorine	The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.	Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.	Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.	Not a concern for lawns and beds at municipal levels.
Turbidity and sediment	Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.	SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.	The practical cost is blocked cartridges, marked laundry and scoured pump seals.	Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.
Pressure and flow	Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.	A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.	Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.	Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.

Read these first for this situation

E. coli and coliforms
Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.
Drinking and kitchens
SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.
Bathrooms, laundry and hot water
The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.
Irrigation and grounds
Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Free chlorine
The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.
Drinking and kitchens
Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.
Bathrooms, laundry and hot water
Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.
Irrigation and grounds
Not a concern for lawns and beds at municipal levels.
Turbidity and sediment
Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.
Drinking and kitchens
SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.
Bathrooms, laundry and hot water
The practical cost is blocked cartridges, marked laundry and scoured pump seals.
Irrigation and grounds
Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.
Pressure and flow
Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.
Drinking and kitchens
A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.
Bathrooms, laundry and hot water
Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.
Irrigation and grounds
Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.

Show every line on the analysis

The rest of the analysis
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
Hardness	Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.	SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.	This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.	Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
Iron and manganese	Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.	SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.	This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.	Stains paving and walls, and iron slime blocks drippers and nozzles.
pH	Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.	SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.	Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.	Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.
TDS (the dissolved salt)	Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.	SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.	High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.	Relevant as salinity for plants and lawns rather than as a health figure.

The rest of the analysis

Hardness
Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.
Drinking and kitchens
SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.
Bathrooms, laundry and hot water
This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.
Irrigation and grounds
Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
Iron and manganese
Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.
Drinking and kitchens
SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.
Bathrooms, laundry and hot water
This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.
Irrigation and grounds
Stains paving and walls, and iron slime blocks drippers and nozzles.
pH
Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.
Drinking and kitchens
SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.
Bathrooms, laundry and hot water
Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.
Irrigation and grounds
Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.
TDS (the dissolved salt)
Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.
Drinking and kitchens
SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.
Bathrooms, laundry and hot water
High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.
Irrigation and grounds
Relevant as salinity for plants and lawns rather than as a health figure.

Sources: SANS 241:2025 for drinking-water limits; SANS 10252-1 for water installations, backflow prevention and drains; manufacturer data for cartridges, housings, media, resin and UV as recorded in the DWT knowledge base. Requirements for connecting an alternative supply, and for registering or licensing a borehole, are set by your municipality and by national water law — they differ by area, so confirm yours rather than relying on this page. Rules of thumb are marked.

Before you call anyone

1Decide what you are actually asking. Water for drinking, kitchens and showers is judged against SANS 241; water for a boiler, a cooling tower or the irrigation is judged against what that equipment needs. Tell the laboratory what the water is used for and it will quote the right analysis instead of the cheapest one.
2Arrange the laboratory before you sample, and use its bottles and its written instructions. Microbiology and chemistry are not collected the same way, and a microbiology bottle is usually sterile, often carries a preservative and normally needs its headspace left. Ask what holding time that laboratory accepts and book the delivery to suit, because microbiology is on a clock of hours.
3Sample where the question is. The municipal connection, the bottom of the storage tank and the furthest tap on the top floor are three different waters, and a complaint from one unit is not evidence about the other forty. Write down the point, the date and the time on every bottle.
4Take the readings you can take yourself, and keep them. Incoming pressure, the meter at the same time each week, and anything that changed just before the complaints started — a new pump, a tank cleaned, a supply interruption, a hot spell. A trend you can show is worth more to whoever you call than a description of one bad morning.

What fixes it

In the order the water goes through them. Every fix links to a plain-language guide and, where it helps, a calculator.

Storage, pumps and the protected connection
Supply interruptions, an alternative source, or any tank feeding the building.
Tanks sized on the hours you must cover and the building's real demand in those hours; opaque, sealed, screened and reachable for cleaning; a booster set sized on the height and the simultaneous peak rather than on the tank outlet; and backflow protection on the municipal connection so nothing can flow the wrong way. What backflow device is required, and whether an alternative supply must be registered or notified, is set by your municipality and by national water law — confirm both before connecting, and use a registered plumber.
Backup water: tanks, boreholes and rain When the tap cannot be trusted Listen to the episode
Sediment filtration at the point of entry
Discoloured water after interruptions, grit in fittings, and ahead of carbon, softening, UV or RO.
Cartridge housings sized on the building's peak flow, run coarse to fine, with isolation valves and a bypass so a cartridge change does not take the building off water, and a pressure gauge on each side so you can see the cartridge filling rather than guess. Change on the pressure difference, not on the calendar.
Cartridge types compared Choosing a filter housing Listen to the episode
Activated carbon for taste and chlorine
Chlorine taste and smell complaints, and ahead of any membrane.
Carbon removes chlorine, taste, odour and colour. It removes no hardness, no salt and no bacteria, and a spent cartridge protects nothing, so it is a consumable with a service life rather than a fitting. Where the complaint is specifically about drinking water, treating the kitchen taps is far cheaper than treating every litre the building uses.
GAC versus carbon block Free versus total chlorine Listen to the episode
UV disinfection
Stored water, borehole water and rainwater that people will drink or shower in.
Water passes a lamp in a quartz sleeve and the dose inactivates what is in it, adding nothing to the water and leaving no residual behind it. It needs clear water to work: a 5 micron cartridge ahead of it is not optional, and iron, hardness and turbidity all cut the dose. It is sized on the peak flow at a stated dose, mounted so the chamber stays full, and the lamp is replaced on the manufacturer's schedule because output falls long before the lamp stops glowing. UV protects the water passing through it, not the pipework and tanks downstream — where a residual is needed through a reticulation, that is a chlorine conversation.
Why a 5 micron prefilter ahead of UV is mandatory What UV does and does not do Listen to the episode

Understanding a borehole or rain-tank supply

In one line: get a laboratory analysis before you plumb it to anything, decide what the water will be used for, treat it for what the analysis actually shows, and check what your municipality requires before you connect it.

A borehole is untreated groundwater and a rain tank is whatever was on the roof, so both start with an analysis rather than a catalogue. The most useful early decision is what the water is for. Irrigation and toilet flushing ask far less of it than showers, and showers ask less than drinking and kitchens — and a supply that is fine for the gardens is not thereby fine for the taps.

What is usually wrong

Match what people in the building are reporting to what is actually happening, and to the stage that deals with it.

What you seeWhat is happeningThe fix

We have drilled a borehole and want to use it in the building: Start with a full analysis and a decision about which points it will feed. Treatment, storage and the plumbing separation all follow from those two answers, and the municipal requirements for connecting it follow from where you are.; Storage, pumps and the protected connection
Borehole water stains basins, laundry and paving orange or black: Dissolved iron and manganese, which oxidise on contact with air. They are removed by oxidising them deliberately and filtering them out on a catalytic media bed, ahead of anything else.; Iron and manganese removal
Sand and grit in the system since the borehole came online: Fine sand from the aquifer. This needs a backwashing media filter, not cartridges — cartridges on a sandy borehole block within days and become a standing maintenance cost.; Backwashing media filter
We want to use rainwater for the gardens and the toilets: A reasonable use, and a much lower bar than drinking. Keep the roof out of the tank with screens and a first-flush diverter, keep the pipework physically separate and clearly marked, and protect the municipal connection.; Storage, pumps and the protected connection
Is the borehole water safe for people to drink?: Only a SANS 241 analysis answers that, and it has to cover microbiology as well as chemistry. Where people will drink it, plan on disinfection as part of the system and on repeat testing, because groundwater changes with the season and with what happens on the surface above it.; UV disinfection

What to test, and what the numbers mean

Read these first for this situation
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
E. coli and coliforms	Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.	SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.	The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.	Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Turbidity and sediment	Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.	SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.	The practical cost is blocked cartridges, marked laundry and scoured pump seals.	Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.
Iron and manganese	Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.	SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.	This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.	Stains paving and walls, and iron slime blocks drippers and nozzles.
Hardness	Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.	SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.	This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.	Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
TDS (the dissolved salt)	Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.	SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.	High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.	Relevant as salinity for plants and lawns rather than as a health figure.
pH	Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.	SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.	Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.	Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.

Read these first for this situation

E. coli and coliforms
Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.
Drinking and kitchens
SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.
Bathrooms, laundry and hot water
The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.
Irrigation and grounds
Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Turbidity and sediment
Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.
Drinking and kitchens
SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.
Bathrooms, laundry and hot water
The practical cost is blocked cartridges, marked laundry and scoured pump seals.
Irrigation and grounds
Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.
Iron and manganese
Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.
Drinking and kitchens
SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.
Bathrooms, laundry and hot water
This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.
Irrigation and grounds
Stains paving and walls, and iron slime blocks drippers and nozzles.
Hardness
Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.
Drinking and kitchens
SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.
Bathrooms, laundry and hot water
This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.
Irrigation and grounds
Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
TDS (the dissolved salt)
Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.
Drinking and kitchens
SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.
Bathrooms, laundry and hot water
High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.
Irrigation and grounds
Relevant as salinity for plants and lawns rather than as a health figure.
pH
Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.
Drinking and kitchens
SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.
Bathrooms, laundry and hot water
Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.
Irrigation and grounds
Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.

Show every line on the analysis

The rest of the analysis
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
Free chlorine	The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.	Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.	Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.	Not a concern for lawns and beds at municipal levels.
Pressure and flow	Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.	A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.	Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.	Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.

The rest of the analysis

Free chlorine
The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.
Drinking and kitchens
Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.
Bathrooms, laundry and hot water
Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.
Irrigation and grounds
Not a concern for lawns and beds at municipal levels.
Pressure and flow
Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.
Drinking and kitchens
A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.
Bathrooms, laundry and hot water
Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.
Irrigation and grounds
Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.

Before you call anyone

1Decide what you are actually asking. Water for drinking, kitchens and showers is judged against SANS 241; water for a boiler, a cooling tower or the irrigation is judged against what that equipment needs. Tell the laboratory what the water is used for and it will quote the right analysis instead of the cheapest one.
2Arrange the laboratory before you sample, and use its bottles and its written instructions. Microbiology and chemistry are not collected the same way, and a microbiology bottle is usually sterile, often carries a preservative and normally needs its headspace left. Ask what holding time that laboratory accepts and book the delivery to suit, because microbiology is on a clock of hours.
3Sample where the question is. The municipal connection, the bottom of the storage tank and the furthest tap on the top floor are three different waters, and a complaint from one unit is not evidence about the other forty. Write down the point, the date and the time on every bottle.
4Take the readings you can take yourself, and keep them. Incoming pressure, the meter at the same time each week, and anything that changed just before the complaints started — a new pump, a tank cleaned, a supply interruption, a hot spell. A trend you can show is worth more to whoever you call than a description of one bad morning.

What fixes it

In the order the water goes through them. Every fix links to a plain-language guide and, where it helps, a calculator.

Storage, pumps and the protected connection
Supply interruptions, an alternative source, or any tank feeding the building.
Tanks sized on the hours you must cover and the building's real demand in those hours; opaque, sealed, screened and reachable for cleaning; a booster set sized on the height and the simultaneous peak rather than on the tank outlet; and backflow protection on the municipal connection so nothing can flow the wrong way. What backflow device is required, and whether an alternative supply must be registered or notified, is set by your municipality and by national water law — confirm both before connecting, and use a registered plumber.
Backup water: tanks, boreholes and rain When the tap cannot be trusted Listen to the episode
Backwashing media filter
Sand and turbidity on a borehole, or any load a cartridge cannot carry economically.
A fibreglass vessel of filter media with an automatic valve that periodically reverses the flow, lifts the bed and sends the trapped dirt to drain. It handles a load that would block cartridges weekly, and in exchange it needs a drain that can take the backwash flow and a pump that can deliver it. Sizing follows the flow and the media, so it comes from the analysis and the peak demand rather than from the size of the plant room.
How a media filter works Backwashing explained Listen to the episode Calculator
Iron and manganese removal
Orange or black staining, metallic taste, slime in fittings — typically a borehole.
Dissolved iron and manganese are oxidised deliberately, then filtered out on a catalytic media bed. Which oxidant suits depends on the media: some are damaged by chlorine and want air, others need chlorine, so this is one to specify from the analysis and the media data sheet rather than by analogy with another building. It goes ahead of softening, UV and any membrane, because iron fouls all three.
Catalytic media for iron and manganese Backwashing explained Listen to the episode Calculator
Water softener
Hardness costing you elements, geysers, calorifiers and laundry machines.
Resin exchanges the calcium and magnesium that form scale for sodium, and regenerates itself with salt on a schedule the valve controls. It is sized on the measured hardness and the real daily volume, not on the number of units, and a metered valve that regenerates on water used beats a time clock that regenerates whether or not anybody was home. It needs salt kept topped up, a drain, and a bypass. Irrigation is left off it.
How a water softener works Water hardness explained Listen to the episode Calculator
UV disinfection
Stored water, borehole water and rainwater that people will drink or shower in.
Water passes a lamp in a quartz sleeve and the dose inactivates what is in it, adding nothing to the water and leaving no residual behind it. It needs clear water to work: a 5 micron cartridge ahead of it is not optional, and iron, hardness and turbidity all cut the dose. It is sized on the peak flow at a stated dose, mounted so the chamber stays full, and the lamp is replaced on the manufacturer's schedule because output falls long before the lamp stops glowing. UV protects the water passing through it, not the pipework and tanks downstream — where a residual is needed through a reticulation, that is a chlorine conversation.
Why a 5 micron prefilter ahead of UV is mandatory What UV does and does not do Listen to the episode
Reverse osmosis at the drinking points
Brak or high-TDS water where people drink it, or a kitchen that needs a consistent feed.
A membrane that holds dissolved salt back, with pre-filters ahead of it and a drain for the reject stream. It is the only stage here that removes salt, which makes it the answer for brak water and an expensive answer for anything else — treating a whole building by RO wastes water and money when the actual complaint is about drinking. Put it where the water is drunk.
How reverse osmosis works The treatment train: what order and why Listen to the episode Calculator

Investigating a water-quality problem

In one line: work out whether the problem is the supply, the storage or the building's own pipework, because those three have different owners and different fixes, and only one of them is solved by adding a filter.

The most useful thing you can do with a complaint is locate it before spending on it. Water that is wrong at every tap in the building points upstream, to the supply or the storage. Water that is wrong at one tap, or only on the hot side, or only on one floor, points at the building's own plumbing, and no amount of treatment at the point of entry will fix it.

What is usually wrong

Match what people in the building are reporting to what is actually happening, and to the stage that deals with it.

What you seeWhat is happeningThe fix

Residents report discoloured water: Three usual causes with three different answers: a disturbance in the municipal main, sediment stirred up in your own tank, or corroding pipework inside the building. Check whether neighbouring properties see it too, and whether it clears after running.; Sediment filtration at the point of entry
Scale everywhere; geysers and elements keep failing: Hardness. It is measured on the analysis, it is the same for the whole building, and it is the one water problem with a direct running cost attached to it in failed elements and lost efficiency.; Water softener
Complaints about a chlorine taste and smell: The municipal residual doing its job. Carbon removes it, and where the complaint is about drinking water specifically, it is cheaper at the kitchen taps than for the whole building.; Activated carbon for taste and chlorine
One unit complains and the rest do not: Almost always that unit's own plumbing: a dying geyser, a length of old galvanised pipe, a seldom-used branch where water stands. Sample that tap and a known-good tap on the same supply before treating anything centrally.; Sediment filtration at the point of entry
A smell on the hot water only: That points at the hot-water system rather than the supply — the cylinder, its temperature setting and its anode. It is a plumbing and hot-water conversation, and treating the cold feed will not answer it.; Sediment filtration at the point of entry

What to test, and what the numbers mean

Read these first for this situation
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
E. coli and coliforms	Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.	SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.	The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.	Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Free chlorine	The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.	Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.	Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.	Not a concern for lawns and beds at municipal levels.
Hardness	Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.	SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.	This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.	Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
Iron and manganese	Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.	SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.	This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.	Stains paving and walls, and iron slime blocks drippers and nozzles.
pH	Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.	SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.	Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.	Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.
Turbidity and sediment	Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.	SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.	The practical cost is blocked cartridges, marked laundry and scoured pump seals.	Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.

Read these first for this situation

E. coli and coliforms
Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.
Drinking and kitchens
SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.
Bathrooms, laundry and hot water
The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.
Irrigation and grounds
Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Free chlorine
The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.
Drinking and kitchens
Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.
Bathrooms, laundry and hot water
Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.
Irrigation and grounds
Not a concern for lawns and beds at municipal levels.
Hardness
Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.
Drinking and kitchens
SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.
Bathrooms, laundry and hot water
This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.
Irrigation and grounds
Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
Iron and manganese
Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.
Drinking and kitchens
SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.
Bathrooms, laundry and hot water
This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.
Irrigation and grounds
Stains paving and walls, and iron slime blocks drippers and nozzles.
pH
Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.
Drinking and kitchens
SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.
Bathrooms, laundry and hot water
Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.
Irrigation and grounds
Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.
Turbidity and sediment
Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.
Drinking and kitchens
SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.
Bathrooms, laundry and hot water
The practical cost is blocked cartridges, marked laundry and scoured pump seals.
Irrigation and grounds
Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.

Show every line on the analysis

The rest of the analysis
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
TDS (the dissolved salt)	Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.	SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.	High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.	Relevant as salinity for plants and lawns rather than as a health figure.
Pressure and flow	Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.	A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.	Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.	Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.

The rest of the analysis

TDS (the dissolved salt)
Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.
Drinking and kitchens
SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.
Bathrooms, laundry and hot water
High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.
Irrigation and grounds
Relevant as salinity for plants and lawns rather than as a health figure.
Pressure and flow
Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.
Drinking and kitchens
A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.
Bathrooms, laundry and hot water
Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.
Irrigation and grounds
Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.

Before you call anyone

1Decide what you are actually asking. Water for drinking, kitchens and showers is judged against SANS 241; water for a boiler, a cooling tower or the irrigation is judged against what that equipment needs. Tell the laboratory what the water is used for and it will quote the right analysis instead of the cheapest one.
2Arrange the laboratory before you sample, and use its bottles and its written instructions. Microbiology and chemistry are not collected the same way, and a microbiology bottle is usually sterile, often carries a preservative and normally needs its headspace left. Ask what holding time that laboratory accepts and book the delivery to suit, because microbiology is on a clock of hours.
3Sample where the question is. The municipal connection, the bottom of the storage tank and the furthest tap on the top floor are three different waters, and a complaint from one unit is not evidence about the other forty. Write down the point, the date and the time on every bottle.
4Take the readings you can take yourself, and keep them. Incoming pressure, the meter at the same time each week, and anything that changed just before the complaints started — a new pump, a tank cleaned, a supply interruption, a hot spell. A trend you can show is worth more to whoever you call than a description of one bad morning.

What fixes it

In the order the water goes through them. Every fix links to a plain-language guide and, where it helps, a calculator.

Sediment filtration at the point of entry
Discoloured water after interruptions, grit in fittings, and ahead of carbon, softening, UV or RO.
Cartridge housings sized on the building's peak flow, run coarse to fine, with isolation valves and a bypass so a cartridge change does not take the building off water, and a pressure gauge on each side so you can see the cartridge filling rather than guess. Change on the pressure difference, not on the calendar.
Cartridge types compared Choosing a filter housing Listen to the episode
Activated carbon for taste and chlorine
Chlorine taste and smell complaints, and ahead of any membrane.
Carbon removes chlorine, taste, odour and colour. It removes no hardness, no salt and no bacteria, and a spent cartridge protects nothing, so it is a consumable with a service life rather than a fitting. Where the complaint is specifically about drinking water, treating the kitchen taps is far cheaper than treating every litre the building uses.
GAC versus carbon block Free versus total chlorine Listen to the episode
Water softener
Hardness costing you elements, geysers, calorifiers and laundry machines.
Resin exchanges the calcium and magnesium that form scale for sodium, and regenerates itself with salt on a schedule the valve controls. It is sized on the measured hardness and the real daily volume, not on the number of units, and a metered valve that regenerates on water used beats a time clock that regenerates whether or not anybody was home. It needs salt kept topped up, a drain, and a bypass. Irrigation is left off it.
How a water softener works Water hardness explained Listen to the episode Calculator
UV disinfection
Stored water, borehole water and rainwater that people will drink or shower in.
Water passes a lamp in a quartz sleeve and the dose inactivates what is in it, adding nothing to the water and leaving no residual behind it. It needs clear water to work: a 5 micron cartridge ahead of it is not optional, and iron, hardness and turbidity all cut the dose. It is sized on the peak flow at a stated dose, mounted so the chamber stays full, and the lamp is replaced on the manufacturer's schedule because output falls long before the lamp stops glowing. UV protects the water passing through it, not the pipework and tanks downstream — where a residual is needed through a reticulation, that is a chlorine conversation.
Why a 5 micron prefilter ahead of UV is mandatory What UV does and does not do Listen to the episode
Reverse osmosis at the drinking points
Brak or high-TDS water where people drink it, or a kitchen that needs a consistent feed.
A membrane that holds dissolved salt back, with pre-filters ahead of it and a drain for the reject stream. It is the only stage here that removes salt, which makes it the answer for brak water and an expensive answer for anything else — treating a whole building by RO wastes water and money when the actual complaint is about drinking. Put it where the water is drunk.
How reverse osmosis works The treatment train: what order and why Listen to the episode Calculator

Looking after an existing treatment system

In one line: find out what is installed and what each part is for, change consumables on the evidence rather than the calendar, and keep the model numbers and the manuals where the next person will find them.

Most of the plant rooms we are called to were installed correctly and then inherited by somebody who was never shown what they had. The equipment is rarely the problem. The problem is that nobody knows what the vessels contain, when the cartridges were last changed, or which of the three pressure gauges matters — so nothing is watched, and the first sign of trouble is a complaint rather than a reading.

What is usually wrong

Match what people in the building are reporting to what is actually happening, and to the stage that deals with it.

What you seeWhat is happeningThe fix

Nobody knows what the plant room actually does: Start by photographing every label and tracing the pipework in order from the incoming main. What each vessel contains and what each stage is for is the first thing the branch will ask you, and it is answerable in an afternoon.; Identify what is installed
Pressure has dropped across the whole building: The commonest cause is filter cartridges that have done their work and are now the restriction. That is what the gauges on either side of the housings are for: a rising difference between them is the cartridge telling you it is full.; Sediment filtration at the point of entry
The softener has stopped softening: Usually salt: an empty brine tank, or a crust bridged across it so the salt never reaches the water. Sometimes the valve is no longer regenerating. Check the salt first, because it is free to check and it is most often the answer.; Water softener
The UV alarm is on, or nobody remembers changing the lamp: A UV lamp loses output long before it stops glowing, so it is replaced on the manufacturer's schedule rather than on failure, and the quartz sleeve is cleaned with it. A lit lamp is not evidence of a working dose.; UV disinfection
A filter vessel seems to run to drain more than it should: A backwashing vessel is supposed to run to drain on its cycle, so the question is whether the frequency and duration match how it was set up. A valve stuck in backwash, or set to regenerate far too often, shows up on the water bill first.; Backwashing media filter

What to test, and what the numbers mean

Read these first for this situation
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
Pressure and flow	Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.	A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.	Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.	Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.
Hardness	Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.	SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.	This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.	Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
Free chlorine	The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.	Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.	Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.	Not a concern for lawns and beds at municipal levels.
Turbidity and sediment	Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.	SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.	The practical cost is blocked cartridges, marked laundry and scoured pump seals.	Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.

Read these first for this situation

Pressure and flow
Not a laboratory line, but the reading that explains most complaints and sizes every stage. Incoming pressure at the connection, and the difference across each filter housing.
Drinking and kitchens
A rising difference across a housing is the cartridge filling up. That difference, logged weekly, is the cheapest instrument in the plant room.
Bathrooms, laundry and hot water
Peak simultaneous demand, not the number of units, sizes the treatment. Mornings and evenings in a residential block, and check-out time in a hotel, are the moments that matter.
Irrigation and grounds
Irrigation usually runs at night on its own zone; note it separately so it is not double-counted into the building's peak.
Hardness
Calcium and magnesium as mg/L CaCO₃ — the white crust on elements, showerheads and kettles. A strip or drop-count kit reads it on site.
Drinking and kitchens
SANS 241 sets no health limit for hardness; it is an operating cost, not a safety number.
Bathrooms, laundry and hot water
This is where hardness costs money: geysers, calorifiers, dishwashers and laundry machines. Scale shows from about 120 mg/L and a softener starts earning its keep from about 200 (rule of thumb); size it on the measured hardness and the real daily volume.
Irrigation and grounds
Not a problem for plants, and irrigation water is not softened — the sodium a softener adds is the wrong thing to put on soil.
Free chlorine
The municipal residual, and the simplest reading you can take yourself with a pool-style DPD kit. Its absence in a tank tells you the protection has run out.
Drinking and kitchens
Present at the municipal connection, usually a fraction of a mg/L. If it is gone by the kitchen tap, ask what happened between the two points.
Bathrooms, laundry and hot water
Taste and smell complaints usually come from here, and carbon is the answer where the complaint is genuine.
Irrigation and grounds
Not a concern for lawns and beds at municipal levels.
Turbidity and sediment
Cloudiness and grit. It is the complaint residents notice first, it blocks cartridges, and it shields bacteria from UV and chlorine.
Drinking and kitchens
SANS 241 sets 1 NTU as the operational limit and 5 NTU as the aesthetic one. Below 5 it can still look clear in a glass.
Bathrooms, laundry and hot water
The practical cost is blocked cartridges, marked laundry and scoured pump seals.
Irrigation and grounds
Drip and micro-irrigation blocks long before people notice the water looks cloudy; filter it whatever the source.

Show every line on the analysis

The rest of the analysis
The line on the certificate	What it tells you	Drinking and kitchens	Bathrooms, laundry and hot water	Irrigation and grounds
E. coli and coliforms	Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.	SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.	The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.	Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Iron and manganese	Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.	SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.	This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.	Stains paving and walls, and iron slime blocks drippers and nozzles.
pH	Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.	SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.	Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.	Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.
TDS (the dissolved salt)	Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.	SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.	High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.	Relevant as salinity for plants and lawns rather than as a health figure.

The rest of the analysis

E. coli and coliforms
Bacteria from sewage, animals, roofs or a dirty tank. E. coli means faecal contamination; coliforms on their own still mean something is getting in. Neither can be seen, tasted or measured on site — this is a laboratory line.
Drinking and kitchens
SANS 241: E. coli not detected in 100 mL, total coliforms under 10. There is no acceptable level for water people drink or wash food in.
Bathrooms, laundry and hot water
The same standard applies: showers and baths are ingestion and inhalation routes, and a laundry does not sterilise what it washes.
Irrigation and grounds
Irrigation of lawns and beds tolerates more than drinking water, but the standard tightens sharply where the water reaches food crops or where people are wetted by sprinklers.
Iron and manganese
Orange and grey-black staining, metallic taste, and a slime that blocks fittings. Common on boreholes, and sometimes from the building's own old steel pipework.
Drinking and kitchens
SANS 241 aesthetic limits are 0.3 mg/L iron and 0.1 mg/L manganese; both stain and taste well before they are a health question.
Bathrooms, laundry and hot water
This is what stains basins, marks laundry permanently and fouls everything downstream, UV sleeves included.
Irrigation and grounds
Stains paving and walls, and iron slime blocks drippers and nozzles.
pH
Below about 6.5 the water is aggressive to copper and steel; above about 8 it drops scale more readily. Rain tanks sit low, some boreholes sit low, municipal water is corrected.
Drinking and kitchens
SANS 241 allows 5 to 9.7, which is wider than what your pipework prefers.
Bathrooms, laundry and hot water
Low pH shows up as green staining and pinholes in copper — a building-fabric cost rather than a health one. A calcite stage raises it without dosing.
Irrigation and grounds
Matters mostly where it drives scaling in irrigation lines; 6.5 to 8.4 is the usual comfortable band.
TDS (the dissolved salt)
Everything dissolved, in mg/L. A pocket meter reads it in seconds. It is an aesthetic and process number: it says nothing about whether the water is safe.
Drinking and kitchens
SANS 241 sets 1 200 mg/L as an aesthetic limit; people taste it well below that, which is where the bottled-water complaints start.
Bathrooms, laundry and hot water
High TDS drives scaling and corrosion in hot water, and it is the number that decides whether reverse osmosis is on the table.
Irrigation and grounds
Relevant as salinity for plants and lawns rather than as a health figure.

Before you call anyone

1Decide what you are actually asking. Water for drinking, kitchens and showers is judged against SANS 241; water for a boiler, a cooling tower or the irrigation is judged against what that equipment needs. Tell the laboratory what the water is used for and it will quote the right analysis instead of the cheapest one.
2Arrange the laboratory before you sample, and use its bottles and its written instructions. Microbiology and chemistry are not collected the same way, and a microbiology bottle is usually sterile, often carries a preservative and normally needs its headspace left. Ask what holding time that laboratory accepts and book the delivery to suit, because microbiology is on a clock of hours.
3Sample where the question is. The municipal connection, the bottom of the storage tank and the furthest tap on the top floor are three different waters, and a complaint from one unit is not evidence about the other forty. Write down the point, the date and the time on every bottle.
4Take the readings you can take yourself, and keep them. Incoming pressure, the meter at the same time each week, and anything that changed just before the complaints started — a new pump, a tank cleaned, a supply interruption, a hot spell. A trend you can show is worth more to whoever you call than a description of one bad morning.

What fixes it

In the order the water goes through them. Every fix links to a plain-language guide and, where it helps, a calculator.

Identify what is installed
Before anything else, on any system you inherited rather than specified.
Walk the pipework in order from the incoming main and photograph every label: vessel size and media, valve model, cartridge housing size, UV model, pump plate. Note which points each branch feeds. This costs an afternoon, it is the first thing anyone you call will ask for, and it is the difference between a quote for what you have and a quote for what somebody guessed.
The treatment train: what order and why The commissioning faults we see most Listen to the episode
Sediment filtration at the point of entry
Discoloured water after interruptions, grit in fittings, and ahead of carbon, softening, UV or RO.
Cartridge housings sized on the building's peak flow, run coarse to fine, with isolation valves and a bypass so a cartridge change does not take the building off water, and a pressure gauge on each side so you can see the cartridge filling rather than guess. Change on the pressure difference, not on the calendar.
Cartridge types compared Choosing a filter housing Listen to the episode
Activated carbon for taste and chlorine
Chlorine taste and smell complaints, and ahead of any membrane.
Carbon removes chlorine, taste, odour and colour. It removes no hardness, no salt and no bacteria, and a spent cartridge protects nothing, so it is a consumable with a service life rather than a fitting. Where the complaint is specifically about drinking water, treating the kitchen taps is far cheaper than treating every litre the building uses.
GAC versus carbon block Free versus total chlorine Listen to the episode
Water softener
Hardness costing you elements, geysers, calorifiers and laundry machines.
Resin exchanges the calcium and magnesium that form scale for sodium, and regenerates itself with salt on a schedule the valve controls. It is sized on the measured hardness and the real daily volume, not on the number of units, and a metered valve that regenerates on water used beats a time clock that regenerates whether or not anybody was home. It needs salt kept topped up, a drain, and a bypass. Irrigation is left off it.
How a water softener works Water hardness explained Listen to the episode Calculator
Backwashing media filter
Sand and turbidity on a borehole, or any load a cartridge cannot carry economically.
A fibreglass vessel of filter media with an automatic valve that periodically reverses the flow, lifts the bed and sends the trapped dirt to drain. It handles a load that would block cartridges weekly, and in exchange it needs a drain that can take the backwash flow and a pump that can deliver it. Sizing follows the flow and the media, so it comes from the analysis and the peak demand rather than from the size of the plant room.
How a media filter works Backwashing explained Listen to the episode Calculator
UV disinfection
Stored water, borehole water and rainwater that people will drink or shower in.
Water passes a lamp in a quartz sleeve and the dose inactivates what is in it, adding nothing to the water and leaving no residual behind it. It needs clear water to work: a 5 micron cartridge ahead of it is not optional, and iron, hardness and turbidity all cut the dose. It is sized on the peak flow at a stated dose, mounted so the chamber stays full, and the lamp is replaced on the manufacturer's schedule because output falls long before the lamp stops glowing. UV protects the water passing through it, not the pipework and tanks downstream — where a residual is needed through a reticulation, that is a chlorine conversation.
Why a 5 micron prefilter ahead of UV is mandatory What UV does and does not do Listen to the episode

Looking after what is installed

Most plant rooms fail through neglect rather than through equipment faults, and most of the neglect is simply nobody knowing what to watch. These are the things worth having to hand and the changes worth acting on.

Have this to hand

A photograph of every equipment label: vessel size and media, valve model, housing size, UV model, pump plate.
The manuals, or the model numbers that let you find them again.
A simple log: incoming pressure, the pressure on each side of the filter housings, and the meter reading, taken at the same time each week.
The date of the last cartridge change, lamp change and media change, and who did each one.
The most recent laboratory analysis, with the sampling point written on it.

What a change usually means

The pressure difference across a filter housing is climbing: The cartridge is doing its job and filling up. This is the intended signal to change it; a fixed calendar interval either wastes cartridges or runs them past useful life.
Pressure or flow has dropped across the whole building: Usually blocked cartridges, sometimes a fouled media bed or a valve stuck mid-cycle. Check the gauges first, because they tell you which stage before anyone opens anything.
Staining or a taste that was not there last month: Something upstream changed: a source switched over, a tank stirred up, a media bed exhausted, or a carbon cartridge past its life. Note when it started and whether it is at every tap or only some.
The softener has stopped softening: Check the salt before anything else: an empty brine tank, or a crust bridged across it so the salt never dissolves, accounts for most cases. If the salt is fine, the valve is not completing its cycle.
A UV alarm, or a lamp nobody remembers replacing: Output falls long before a lamp goes dark, so a lit lamp is not evidence of a working dose. Replace on the manufacturer's schedule and clean the sleeve with it. Treat the water as undisinfected until it is done.
A vessel running to drain far more often than it used to: A valve stuck in backwash or set to regenerate too frequently. It shows on the water bill before it shows anywhere else, which is why the meter reading belongs in the weekly log.

What to send us

What changed, and when it started.
Whether it affects every tap, one floor or one unit, and whether it is on hot, cold or both.
The readings from your log, especially the pressures either side of the housings.
Photographs of the labels and of the plant room as it stands.
The latest laboratory analysis and where the sample was taken.
What the building actually uses in a day, and its peak hours.

Service intervals, cleaning methods and replacement parts come from the manufacturer's instructions for your actual equipment. What is here helps you notice a change and describe it accurately; it does not replace that documentation, and it is not a substitute for the installer where the work needs one.

How the equipment works

Four animations of the equipment most often found in a plant room. Switch the state and watch the water; each one links to the full guide.

What the cartridges in the housings are doing

The two shapes behave differently, and only one of them cares which way up it goes in.

Sediment cartridges and carbon blocks work from the outside in: water fills the housing around the cartridge and is forced through its wall to the hollow centre. These are hollow right through and the same at both ends, so they go in either way up. When the pressure difference across the housing climbs, this is the cartridge filling with what it caught.

Read the full guide

The UV unit, and why its mounting matters

The lamp only treats water it can reach, and the water is also what keeps the lamp cool.

Upright with the inlet at the bottom and the outlet at the top: air leaves through the outlet, the chamber stays full and every litre passes the whole lamp.

Read the full guide

The media vessel and its valve

This is the equipment that cleans itself, and the reason a plant room needs a drain.

Water enters through the valve, passes down through the media bed, is collected at the bottom and rises up the centre tube to the building. The dirt it removes stays in the top of the bed.

Read the full guide

The softener and its salt tank

Why the salt tank matters, and what the valve is doing when it runs at night.

Hard water passes down through the resin beads, which hold the calcium and magnesium and release sodium in their place. Softened water rises up the centre tube to the building, and the resin slowly fills up with hardness.

Read the full guide

Things people hear that are not true

The ones we correct most often.

We have tanks, so we have water security.
Storage solves continuity, not quality. The day the tank goes in, the building gains a warm dark vessel in which the municipal residual fades and biology restarts. Treat what leaves the tank, keep it sealed and dark, and clean it on a schedule.
It is municipal water, so it is safe by the time it reaches the flat.
It was safe at the connection. What happens between there and the tap — a tank, a long dead leg, old galvanised pipe, a hot-water cylinder — is the building's responsibility, and it is where most complaints actually originate.
We had the water tested when the system went in.
That result described one day at one point. Boreholes change with the season and the water table, tanks change with what grows in them, and pipework changes as it ages. A single historic certificate is not a current answer.
The water is clear, so it is fine.
Clear water can carry bacteria, nitrate and dissolved metals, none of which have a look, a taste or a smell. Clarity rules out sediment and nothing else.
A filter is a filter — we will put one in and be covered.
Each stage does one job. Sediment removes grit, carbon removes taste and chlorine, softening removes hardness, UV inactivates microorganisms, and reverse osmosis removes dissolved salt. Fitting the wrong one costs money and fixes nothing; the analysis says which you need.
A UV lamp is working because it is glowing.
Lamp output falls steadily from the day it is switched on, and the eye cannot see the difference. That is why lamps are replaced on the manufacturer's schedule rather than on failure, and why the quartz sleeve is cleaned at the same time.
Softened water and filtered water mean the water is drinkable.
Softening exchanges hardness for sodium and filtration removes particles and taste. Neither is disinfection, and neither removes nitrate or dissolved metals. Whether a supply is fit to drink is a laboratory question, not an equipment question.

The questions we get asked

Short answers. Every one ends in a next step.

Who is responsible for water quality in a complex or an estate?

The municipality is responsible for what it delivers to the connection. From that point inward, the water installation belongs to the property, which in a sectional-title scheme normally makes it the body corporate's common property and the trustees' responsibility to maintain. Where the scheme has added storage or an alternative source, it has also taken on the quality of what those deliver. Your managing agent and your scheme's rules set out who signs off the work.

When the tap cannot be trusted

What should I give a contractor so that competing quotes are comparable?

Five things, and the same five to everyone: the laboratory analysis with its sampling point and date; what the water is used for and which points it must serve; the peak simultaneous demand and the daily volume; a photograph of the existing plant room with the equipment labels legible; and the space, drain and power available. Quotes that answer the same brief can be compared. Quotes built on different assumptions cannot, and the cheapest is usually the one that assumed the least.

How often should the water be tested?

It depends on the source and on what the water is used for, and where a scheme is legally obliged to monitor, that obligation sets the frequency rather than a rule of thumb. As a working position: municipal supply into simple storage needs testing far less often than a borehole people drink from, and any borehole or rain supply used for drinking is worth testing at least annually and after anything changes — a new pump, a wet season, work on the ground nearby. Test when something changes, not only on a calendar.

Do we need permission to drill or use a borehole?

Very likely something is required, and what it is depends on where you are and what you intend to use the water for. Municipalities differ on registration, metering and what may be connected to a building's plumbing, and national water law governs abstraction beyond limited domestic use. Ask your municipality before drilling and again before connecting it to anything, and keep whatever they give you in writing. We can tell you how to treat the water; we cannot tell you what your council will permit.

Residents are complaining about the taste. Where do I start?

Establish how widespread it is before spending anything. Ask whether it is at every tap or a few, hot or cold or both, all day or first thing in the morning, and whether neighbouring properties on the same street notice it. A complaint from one unit that clears after running the tap is that unit's plumbing. A complaint from the whole building that does not clear is upstream, and that is where a sample and a look at the tanks earn their keep.

Is a whole-building system better than treating the drinking points?

They answer different questions. Anything protecting the building — sediment, softening for the hot-water plant, disinfection of stored water — belongs at the point of entry, because that is what it is protecting. Anything about how the water tastes to drink belongs at the kitchen taps, where the volume is a fraction of the building's total and so is the cost. Treating every litre a building flushes and irrigates with to improve the taste of the few litres people drink is the most common way to overspend here.

What does a system like this cost to run?

The running cost is consumables and attention rather than the equipment: cartridges changed on pressure difference, salt for a softener, a UV lamp and sleeve on schedule, media replaced at intervals measured in years, and the water a backwashing vessel or an RO sends to drain. We do not publish prices; send the branch what is installed and what the building uses and it will come back with the consumables list and the intervals your equipment actually calls for.

What should I send the branch?

The laboratory analysis if you have one, a photograph of the plant room with the labels readable, what the building uses in a day and at its peak, which points need treating, and a description of what changed and when. That is enough for a useful answer. If you do not have an analysis yet, say so and ask which one to order for what you are trying to do — it is a cheaper first step than a system nobody sized.

Talk to a person

Phone or WhatsApp the branch nearest you. Send a photo of your water certificate and we will tell you what we see. We quote from your analysis and your flow, and we do not publish prices.

Cape Town

5 Firgrove Way, Firgrove Industrial Estate, Macassar, 7134

+27 21 851 0133

Mon to Thu 08:30 to 16:30, Fri 08:30 to 16:00

sales@definitivewater.co.za

Johannesburg

Unit 067, Inospace Allandale Exchange, 917 Morkels Close, Halfway House, Midrand, 1685

+27 75 084 5743 WhatsApp Johannesburg

Mon to Thu 08:30 to 16:30, Fri 08:30 to 16:00

salesjhb@definitivewater.co.za

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Guides, episodes and calculators

The knowledge-base guides that building and site managers use most, each with a podcast episode, in English and Afrikaans.

All the episodes All the guides

Hardness converter TDS and conductivity Vessel and valve selector Media filter sizing Unit converter

Treatment train designersoon

Type in your certificate and get a suggested treatment train. Opening soon, as a calculator, not a guarantee.

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General guidance for South African buildings and sites. What a particular building needs follows from its water, its demand and its existing installation; a laboratory result and a conversation with the branch come before any purchase, and the branch confirms the exact product codes. Nothing here establishes that a supply is safe to drink or that a connection is permitted where you are.

These guides are general information, compiled from published standards, manufacturer data and our own experience, and we keep them as accurate as we can. They are not a design, a specification or advice for a particular site. Whoever specifies, installs or operates a system, whether an engineer, an installer, a farmer or a plant manager, remains responsible for checking that what is written here applies to their water and their installation, and for the work itself. Definitive Water Technologies accepts no liability for errors in these pages or for work done on the strength of them. When in doubt, send us the analysis and talk to the branch.

Water the building can rely on.

Start here: what are you dealing with?

Keeping water available through interruptions

What is usually wrong

What to test, and what the numbers mean

Read these first for this situation

The rest of the analysis

What fixes it

Storage, pumps and the protected connection

Sediment filtration at the point of entry

Activated carbon for taste and chlorine

UV disinfection

Understanding a borehole or rain-tank supply

What is usually wrong

What to test, and what the numbers mean

Read these first for this situation

The rest of the analysis

What fixes it

Storage, pumps and the protected connection

Backwashing media filter

Iron and manganese removal

Water softener

UV disinfection

Reverse osmosis at the drinking points

Investigating a water-quality problem

What is usually wrong

What to test, and what the numbers mean

Read these first for this situation

The rest of the analysis

What fixes it

Sediment filtration at the point of entry

Activated carbon for taste and chlorine

Water softener

UV disinfection

Reverse osmosis at the drinking points

Looking after an existing treatment system

What is usually wrong

What to test, and what the numbers mean

Read these first for this situation

The rest of the analysis

What fixes it

Identify what is installed

Sediment filtration at the point of entry

Activated carbon for taste and chlorine

Water softener

Backwashing media filter

UV disinfection

Looking after what is installed

Have this to hand

What a change usually means

What to send us

How the equipment works

What the cartridges in the housings are doing

The UV unit, and why its mounting matters

The media vessel and its valve

The softener and its salt tank

Things people hear that are not true

The questions we get asked

Talk to a person

Cape Town

Johannesburg

Guides, episodes and calculators