Quick answer
Mains pressure above 600 kPa stresses geysers, valves, tap seals and fittings, and it is a leading cause of leaks that appear to have no explanation. Johannesburg's hillier suburbs regularly run well above that, especially overnight when demand drops. A pressure-reducing valve at the meter brings it down to a safe 400 kPa and stops you replacing the same components year after year.
Common causes
- No pressure-reducing valve installed on the incoming main
- Failed PRV that has drifted open or seized
- Elevation — properties low on a hill carry the head of everything above them
- Overnight pressure peaks when municipal demand falls away
- PRV set correctly but undersized for the incoming supply
What you can do now
- 1Buy an inexpensive pressure gauge that screws onto a garden tap
- 2Read it overnight and first thing in the morning, when pressure peaks
- 3Record readings over a few days rather than relying on one measurement
- 4Note whether valves, tap washers or geyser components have been failing repeatedly — that is the symptom high pressure produces
- 5Check whether a PRV already exists at the meter before quoting for a new one
When to call a professional
Above 600 kPa, fit a pressure-reducing valve. Above 800 kPa, treat it as this month's job — at that pressure geyser valves, tap seals and pipe joints are all being worked beyond their design range and failures cluster. A plumber will fit and set the PRV at the meter and verify the downstream pressure, which also protects the geyser's safety valve from constant operation.
Typical cost in Johannesburg
PRV supplied + fitted R1,800–R2,800
Indicative ranges only. We provide written, itemised quotes before any work.
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