Dripping mixer tap – is a new seal enough to fix it?
A dripping mixer tap seems like a minor annoyance until you notice the water bill has crept up and a limescale streak has formed under the basin. The question usually isn't whether the leak can be fixed, but whether fixing this particular tap is still worthwhile.
Not all mixer taps are alike. A two-handle compression tap, a single-lever cartridge tap and a thermostatic mixer all leak for different reasons and are repaired in completely different ways.
Below we look at how to identify the type of leak, what the location of the dripping tells you, and when replacing the seal is only buying time.
Where exactly the water is coming from – three different leaks
Before you unscrew anything, spend a minute watching where the water is actually escaping from. That one observation decides half the repair.
- Dripping from the spout with the lever off — the internal shut-off mechanism (cartridge or valve head) no longer seals
- Water seeping from under the lever or around the spout — the O-rings are worn or scratched
- Water dripping from underneath the basin, from the connection hoses — it's the hose or its seal, not the tap itself
- Moisture appears only when the tap is open — this is a pressurised connection issue, not a shut-off fault
The paper towel test
Dry the tap and the area underneath it completely and place a dry paper towel below. Check after an hour where the wet patch is. This tells you whether the water is coming from a drip above or a connection below — two repairs with entirely different cost and effort.
When a seal or cartridge helps
A classic two-handle tap has a ceramic or rubber-sealed valve head under each handle. If only the hot or only the cold side drips, that one head is faulty and replacing it is a cheap, simple job.
On a single-lever tap, a ceramic cartridge handles the shut-off. If a replacement cartridge is available and the tap body is sound, replacing the cartridge is a sensible fix even on a more expensive tap.
Water seeping from under the lever is usually an O-ring problem. These can be replaced, but if the housing is scaled and scratched inside, a new ring will start leaking again within weeks.
Why a new seal sometimes doesn't help
Tallinn's tap water can be fairly hard in places. Limescale scratches ceramic discs and leaves microscopic grooves on the sealing surface. A new seal is pressed against the same damaged surface, and the dripping returns within a few weeks.
If you've already replaced the seal on this tap once and the leak came back, a second attempt usually isn't worth the cost.
When a new tap is cheaper than a repair
Replacing the tap is generally the more sensible option when the body is corroded through, spare parts are no longer available, or it's a cheap, unbranded model whose cartridge isn't a standard size.
The same applies when the tap is over ten years old and other bathroom work is planned anyway. If replacement is needed, our plumbers can handle the full plumbing job; if repair still makes sense, ask them to assess the cartridge and seals on site.
- The body has corroded green or cracked — repair is out of the question
- No cartridge is available for the model — replace the tap
- The angle valves no longer shut off properly — replace them together with the tap
- The dripping has returned after a previous seal replacement
What dripping actually costs
One drop per second adds up to several dozen litres a day. In an apartment block where hot water is metered separately, a dripping hot tap also means wasted heating energy on top of the water cost.
Constant moisture also leaves limescale streaks on the basin that etch into the surface and can no longer be removed later.
How to prepare for the repair
Close the angle valves and open the tap to release the pressure. If the angle valves won't close, that's a separate sign the connection already has a problem.
Photograph the tap and the connection underneath it. With these two photos a technician can bring the right spare part in advance and finish the job in a single visit.
If water is coming from a pressurised hose and the tap can't be shut off, close the flat's main stopcock and call our emergency plumbing service to come out.
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