Why this matters
Cape Town's Level 1 baseline and intermittent Joburg/Tshwane restrictions make municipal top-up unreliable. A pool that loses 50,000 L/year to evaporation can't be kept up with bottled water — owners need a defensible alternative source.
Rainwater: sizing and components
For a 7 × 3.5 m pool needing ~40,000 L/year of top-up:
- Catchment: 100 m² roof × 600 mm annual rainfall × 0.85 efficiency = ~51,000 L/year — enough for top-up
- Tank: 5,000 L (minimum) to 10,000 L (comfortable) — JoJo or similar
- First-flush diverter: critical for water quality, ~R600–R1,200
- Pre-filter and gauze screen at tank inlet
- Pump or gravity feed to pool
- Turnkey: R12,000–R28,000 installed
Borehole: what most owners get wrong
SA groundwater commonly carries 0.3–3 mg/L iron, 0.1–0.5 mg/L manganese, plus calcium and dissolved organics. Pumped straight to a pool it stains marbelite brown, plates onto fibreglass and clogs salt cells. Required treatment: 50-micron sediment filter, then a manganese-greensand or birm filter, then chlorine dosing to oxidise residual iron, then a final cartridge filter.
Cost and approval
Borehole drilling: R45,000–R120,000 depending on depth and yield. Pump + tank + treatment train: R18,000–R55,000. Borehole registration with the DWS is required for any abstraction above 10 m³/day. No SSEG-style fee for residential use, but a Water Use License may apply in stressed catchments.
Sources
- DWS National Water Act registration — Department of Water and Sanitation
- SAWS rainfall climate data — South African Weather Service