Quick answer
The pressure-control valve is a four to five year wear item, not a fault in the geyser. Once it drips constantly, the diaphragm has perished and the valve can no longer seat. Replacement is quick and inexpensive. What matters is doing it before the drip becomes a flow — a failed-open PCV can drain heated water continuously, and the element keeps paying to reheat what runs down the overflow.
Common causes
- Normal end-of-life wear on the valve diaphragm at four to five years
- Excessive mains pressure above 600 kPa shortening valve life dramatically
- Scale build-up holding the valve seat open so it never fully closes
- Debris from municipal supply work lodging under the seat
- An incorrectly rated valve fitted at installation — the valve must match the cylinder's kPa rating
What you can do now
- 1Place a container under the overflow for an hour to gauge how much hot water is being lost
- 2Check whether the drip is constant or only during heating — constant confirms the valve
- 3Note the kPa rating stamped on the valve so the correct replacement is brought to site
- 4Have mains pressure tested if this is the second valve to fail in a few years
When to call a professional
Book it within the week. A leaking PCV wastes heated water continuously and the next stage of failure is a constant flow rather than a drip. Ask the plumber to check static mains pressure at the same time — if it is over 600 kPa, a pressure-reducing valve will stop you replacing this part every couple of years.
Typical cost in Johannesburg
R950–R1,500
Indicative ranges only. We provide written, itemised quotes before any work.
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