Backflow Preventers on SA Boreholes: Why the Municipality Cares

If you have both borehole and municipal water on your property and they share any plumbing downstream, you are legally required to fit a testable double-check valve (DCV) or reduced-pressure zone (RPZ) device on the municipal inlet. SANS 10252-1 and every SA metro bylaw agree.

Why

A power cut drops municipal pressure. Your borehole pump (still running on inverter or generator) can push untreated borehole water back into the municipal main, contaminating your neighbours. Joburg Water and City of Cape Town have both prosecuted homeowners for this.

What to fit

• DCV (double-check valve) , R900 to R1,600, acceptable for low-risk (garden irrigation only)
• RPZ valve , R3,800 to R6,500, required if borehole water reaches any indoor tap
• Air gap , cheapest and always compliant , tank filled from municipal with a physical air gap, borehole feeds tank only

Installation cost

R1,400 to R2,800 labour, plus annual testing (R650 to R900) for RPZ valves. Testing must be logged by a PIRB or IOPSA-registered plumber.

Iron and manganese in borehole water

See our borehole iron staining guide for treatment.

Find a borehole-certified plumber.