Dripping Taps And Mixer Cartridges

A tap that drips once a second wastes a surprising amount of water over a month, and in a metered building somebody is paying for it.

It is also one of the few plumbing jobs where the repair is genuinely small, provided the right part turns up.

Two completely different taps

Traditional tap sets, with separate hot and cold handles that turn more than a quarter turn. These have a washer and a seat. The handle screws the washer down onto the seat to stop the flow.

Mixers, with one lever that moves for both temperature and flow. These have a cartridge, which is a sealed ceramic assembly, and there is no washer in them.

A washer kit does nothing for a mixer. A cartridge does nothing for a tap set. Which sounds obvious and is the reason a large share of dripping taps take two visits.

Fixing a tap set

The washer is the usual culprit, and it is a rubber disc that has hardened and no longer seals.

Replacing it is quick. What matters is the second half of the job: the seat. The brass seat the washer closes onto gets scored over years, and a new washer on a damaged seat starts dripping again within weeks.

The fix is to re-cut the seat with a reseating tool at the same time as the washer goes in. That is the step that gets skipped, and it is why a tap that was repaired last year is dripping again.

An O-ring on the spindle is the other common fault. That one leaks around the handle rather than out the spout, and it is a different symptom with a different part.

Fixing a mixer

The cartridge is replaced as a unit. They are not serviceable and there is nothing inside to adjust.

The difficulty is that cartridges are not standard. Diameter, length, spline pattern and the fixing method all vary by brand and by model within a brand, and a mixer that is fifteen years old may have a cartridge that is no longer made.

Which means identifying the mixer before ordering. A photograph of the body and the handle usually does it, and where it does not, the cartridge comes out first and the part is matched to it.

Where the cartridge is genuinely unavailable, the mixer is replaced. That is a larger job than it sounds in a tiled wall, because a wall mixer sits in a plate over a hole that was cut for the old body.

The faults that are not the tap

Three symptoms that send people looking at the wrong thing.

A shower that drips long after it is turned off is usually water draining out of the riser rather than a leaking valve. It stops after a minute or two and it is not a fault.

A tap that spits and surges is air in the line or a partly blocked aerator, not a washer. A tap that has lost pressure is the same family of problem as [water pressure in apartments](/blog/water-pressure-problems-in-apartments).

A banging noise when the tap closes is water hammer, which a loose washer can cause and which usually has a different source entirely, set out in [noisy pipes and water hammer](/blog/noisy-pipes-and-water-hammer).

Isolation is the real constraint in an apartment

In a house, the water goes off at the meter and the job proceeds.

In an apartment without isolation valves at the fixture, the water goes off for the riser, which means notifying neighbours, booking a window and working to a deadline. A ten minute tap repair becomes a scheduled event.

Which is why fitting isolation valves while the wall is open is one of the highest return decisions in an older building, and why it has its own case in [isolation valves and why a building needs them](/blog/isolation-valves-and-why-a-building-needs-them).

Doing a whole property at once

Across a portfolio, taps are better dealt with as a sweep than as individual callouts.

Every tap in an apartment serviced in one attendance, with the washers, seats, cartridges and aerators done together and the isolation handled once. It costs a fraction of four separate callouts over a year and it removes the drip complaints before they are logged, which is the same logic as [emergency or scheduled](/blog/emergency-or-scheduled-what-warrants-a-callout).

Ample services taps and mixers across apartments and houses in the eastern suburbs and inner city, with the tiling, waterproofing and wall repairs handled by one team where a wall has to be opened.