The drought under your feet runs late
Borehole water is rainfall that soaked in — so a failed rainy season reaches the aquifer on a delay, and the borehole feels it just as the farm leans on it hardest. How hard it falls depends on the rock. In the Karoo's fractured shales, most boreholes give less than 1 L/s in a good year and have little in reserve. The dolomite of Gauteng and North West holds the country's best groundwater, but even it can be overdrawn: at Tarlton, irrigation from the Steenkoppies dolomite grew more than sevenfold since 1980 and the water levels have been falling steadily since.
There is a second, less obvious loss. As the water level in the borehole drops, the pump must lift from deeper, and it delivers less: the GEOSS groundwater guideline for farmers (2019) shows one common submersible pump giving 30 m³/h with water at 60 m, and only 12.6 m³/h from the same borehole with water at 85 m. Running the pump harder to make up the shortfall is how boreholes get hurt in droughts — burnt-out pumps, sand and iron packed into the pump and screen, clogged water-bearing fractures, sometimes permanent damage.
The water itself changes
A drought-stressed borehole pulls older, deeper water that has spent longer dissolving the rock around it — so the water usually gets saltier as the level falls, a pattern recorded across the western Karoo in recent droughts. Near the coast, an overdrawn aquifer starts pulling in seawater. Drilling deeper is not automatically the fix: South African guidance records fresh shallow aquifers spoiled when deeper drilling let salty water mix upward into them.
Iron and manganese — the minerals behind brown staining, metallic taste and slimy red growth — also behave worse under heavy pumping, clogging screens, pumps and pipes. This is a studied failure mode: the Water Research Commission devoted a full report (2070/1/14) to iron clogging of the Atlantis production boreholes.
All of which means a laboratory certificate from three years ago describes water you no longer have. Borehole water that people drink should be tested at an accredited laboratory against SANS 241 (the South African drinking-water standard) at least once a year — and in a drought, again before each heavy-use season.
Find out what the borehole can really give
The yield quoted on the day of drilling is not what the borehole can sustain. The traditional method — pump flat out for a morning, then use two-thirds of that — routinely flatters the hole: the GEOSS guideline documents a case where it suggested 8–11 m³/h from a borehole that scientific testing showed could sustain only 3.6 m³/h. The proper method is the national standard SANS 10299-4: a stepped pumping test, a constant-rate test of at least 24 hours, and watching how fast the level recovers — interpreted by a geohydrologist before the pump is chosen.
Then keep two habits: dip the water level before the pump starts and again before it stops, and read a flow meter every pumping day. If you abstract more than 2 L/s you are in any case required to record monthly volumes and keep those records for five years. An automatic low-level switch is cheap insurance against pumping the hole dry.
Treat this year's water, not last year's
The treatment ladder for borehole water is well trodden: oxidation plus catalytic media filtration for iron and manganese (the drinking-water limits are 0.3 and 0.1 mg/L — staining starts around there too), a softener where hardness scales kettles, geysers and drip lines, and reverse osmosis once the salt load (TDS — total dissolved solids) climbs toward 1 000 mg/L, the point at which South African practice treats water as a desalination candidate. Drought moves water up this ladder: a filter sized for last year's 0.5 mg/L of iron chokes on this year's 2 mg/L. After every retest, check that the treatment still matches the water.
The paperwork, briefly
Schedule 1 of the National Water Act lets you take water for the household and for grazing stock without a licence. Beyond that: groundwater use above 10 m³/day must be registered with the Department of Water and Sanitation; the general authorisation caps what a property may take (at most 40 000 m³/a, less in many catchments); land near wetlands and rivers may need a full licence; and municipal by-laws add their own step — Cape Town, for instance, requires written notice 14 days before a borehole is sunk. Registration costs nothing. Being unregistered is what gets expensive. The thresholds above come from the general authorisation, which is reissued from time to time and sets different volumes for different catchments, so confirm the current notice for your own quaternary catchment and your own municipality rather than relying on the figures here.
Rule of thumb
Dip the level, meter the flow, and retest the water every year — before every season in a drought. Pump what the yield test proved, not what the drill rig promised. Rebuild the treatment around the newest analysis, and when the salt reading starts climbing toward 1 000 mg/L, start planning for reverse osmosis before the taste tells you to.