Why does a mixer tap leak and how can it be repaired?

Understanding the causes of mixing valve leaks

A leaking mixer tap is a common problem in the home, usually caused by natural wear and tear on internal components. Leaks can occur in two main ways: either through the spout when the faucet is closed, or at the base of the control when in use. In 80% of cases, the source of the problem is the rubber seals or worn ceramic cartridges. Limescale, present in water, considerably accelerates this wear process by accumulating on mechanical parts.

Precise leak diagnosis

Before intervening, it is essential to identify the source of the leak. A leak at the spout usually indicates a defective cartridge or a worn seal. When water escapes from the base of the faucet, the problem is often the seal under the handle. For models equipped with a flexible hose, systematically check the condition of the connections, which can become loose over time. A simple visual and tactile test can usually pinpoint the exact source of the problem.

Step-by-step repair of a mixing valve

Preparation and dismantling

Start by turning off the water supply. Using a suitable screwdriver, remove the decorative cover on the handle to gain access to the fixing screw. Carefully remove the handle, rotating it if necessary. Under the handle, you’ll find the cartridge retaining nut, which you’ll need to unscrew using a wrench or a pair of pliers.

Replacing seals and cartridges

Once the cartridge has been removed, inspect it carefully. Ceramic cartridges often show visible striations when worn. Systematically replace all O-rings on the cartridge and at the bottom of the housing. For older models with single seals, check the condition of the brass seat, which may require light sanding to restore its flatness.

Reassembly and final testing

When reassembling, apply a thin layer of silicone grease to the new seals to ease their installation and extend their life. Carefully replace the new cartridge, making sure it is correctly aligned, then tighten the retaining nut without excessive force. After repositioning the handle, restore the water supply and thoroughly test the seal by gradually opening and closing the tap.