Quick answer
Low pressure comes from a partially closed mains valve, scaled aerators and showerheads, a failing pressure-reducing valve, corroded galvanised supply pipe, or a municipal supply problem. The pattern tells you where to look: low at one tap is that fitting, low on hot only is the geyser side, and low everywhere on both hot and cold is the mains or the incoming pipe.
Common causes
- Partially closed isolation valve or stop-cock, often after unrelated work
- Scaled aerators and showerheads restricting flow at the fitting
- Failing pressure-reducing valve stuck toward closed
- Galvanised pipe corrosion narrowing the bore of the supply line
- Municipal pressure drop, common at peak times and in higher-lying suburbs
- Partially blocked geyser inlet restricting the hot side only
What you can do now
- 1Check the mains stop-cock is fully open — it is the most common and cheapest cause
- 2Unscrew aerators and soak them in vinegar for thirty minutes, then brush and refit
- 3Test hot and cold separately at several taps and note the pattern
- 4Ask a neighbour whether they have the same problem, which points at the municipal supply
- 5Check under-basin isolation valves are fully open, not just partly turned
When to call a professional
If only the hot pressure is low, the geyser inlet or its valves are restricted. If both hot and cold are low throughout the house and the stop-cock is fully open, the problem is on the mains side or in the incoming pipe. Book a plumber to test static and dynamic pressure at the meter — that single measurement separates a municipal problem from a pipe problem on your property.
Typical cost in Johannesburg
PRV replacement R1,400–R2,200 · Investigation R650
Indicative ranges only. We provide written, itemised quotes before any work.
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