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Geyser overflow pipe dripping: normal, or a fault?
A small drip from the geyser’s overflow pipe while the geyser heats is normal: water expands as it warms, and a valve lets the extra out. Kwikot, the geyser maker, says more than about four litres a day, or a constant trickle, is not normal, and means a valve has failed or the thermostat is set too high. Never cap or block the pipe.
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Which pipe is dripping?
A geyser installed to SANS 10254 has up to three pipes that end outside, and each tells you something different. Kwikot’s summary of the standard says the safety valve and the expansion relief valve must each be piped separately to the outside, and the drip tray under the geyser drains outside too.
| Pipe | Comes from | Water from it means |
|---|---|---|
| T&P pipe | The temperature and pressure (T&P) safety valve on the geyser | An occasional drip can be normal. A steady flow means the valve is passing or the water is overheating. |
| Expansion relief pipe | The pressure control valve on the cold supply | Drips while the geyser heats are normal expansion. A constant trickle means the valve has failed. |
| Drip tray pipe | The tray under the geyser | Usually that the tank itself is leaking. Treat it as a geyser about to burst. |
Not sure which is which? Photograph where the pipes come out of the wall or roof and send it to us on WhatsApp.
When a drip is normal
Water expands as it heats, and on a geyser fed at mains pressure that extra volume has to go somewhere, so the expansion relief valve lets a little out during each heating cycle. Kwikot calls a small amount of discharge while the geyser heats normal thermal expansion, and its solar manual treats occasional drips from the safety valve overflow as normal too. The drip should stop once the geyser has finished heating.
When it is a fault
Kwikot draws the line at more than about four litres a day, or a constant trickle. Its three usual causes:
- The T&P valve is passing: letting water through when it should be closed
- The pressure control valve has failed
- The thermostat is set too high, so the water overheats
A valve that runs all day wastes water you pay for. In the City of Cape Town towns, Somerset West to Brackenfell, overflowing geysers are one of the leaks the City’s water rebate specifically excludes, so that water stays on your account.
Never cap or block the overflow pipe
Capping a dripping pipe stops the drip and takes away the geyser’s safety margin. Kwikot calls the relief pipe the tank’s last line of defence, and says blocking it turns a leak into a burst. Fix the valve instead.
If the water is coming from the drip tray
Water in the drip tray, rather than at the overflow pipe, usually means the tank has failed, Kwikot says, and a leaking tank cannot be repaired. Switch the geyser off at the distribution board, close its cold supply, and call us on 081 559 2180 at any hour. It is the start of a burst geyser, and our burst geyser guide covers the insurance claim.
How we fix it
We find which valve is discharging and why, then replace the T&P valve, the pressure control valve or the thermostat as needed, and check the rest of the installation against SANS 10254 while we are in the roof. Send us a photo on WhatsApp first, and Malan will tell you what it looks like.
Questions people ask
Is it normal for a geyser overflow pipe to drip?
A little, while the geyser heats: that is the water expanding. Kwikot says more than about four litres a day, or a constant trickle, is a fault.
Why is water running constantly from my geyser overflow?
Usually a T&P valve that is passing, a failed pressure control valve, or a thermostat set too high. A plumber needs to find which one and replace it.
Can I block or cap the geyser overflow pipe?
No. The relief pipe is the geyser’s last line of defence, and blocking it can turn a leak into a burst.
What does water in the geyser drip tray mean?
Usually that the tank itself is leaking. Switch the geyser off at the distribution board, close its cold supply and call a plumber; a leaking tank has to be replaced.
Related
- Burst geyser: what to doGeyser burst? Switch off the power and water, protect what you can, take photos, then call your insurer and a registered plumber. Step by step, with the claim.
- Geyser repair and replacementBurst or failing geyser in Stellenbosch, Somerset West or Paarl? ProSol repairs and replaces geysers to SANS 10254, with the certificate your insurer asks for.
- Geyser not heating or trippingNo hot water, lukewarm water, or a geyser that trips the power? What to check at the distribution board, what each sign means, and when to call a plumber.
- Emergency plumbingBurst pipe, burst geyser or a leak you cannot stop in Stellenbosch, Somerset West or Paarl? ProSol takes emergency call-outs 24/7. Call 081 559 2180.
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Tell us what’s wrong. We’ll tell you what it takes.
Phone for anything urgent, at any hour. Otherwise send a photo and a few words on WhatsApp, and Malan comes back to you with what it needs. Planned work gets a free written estimate before we start.