How to clean, descale and maintain a boiling water tap

Three jobs, three intervals

A boiling water tap is low-maintenance, but it is not no-maintenance. There are three separate jobs, each on its own clock, and how often you do them depends almost entirely on your local water hardness.

If you are not sure which column you are in, check your city on the installers page. It lists water hardness for 15 UK cities, and anything above 200 mg/l puts you firmly in the right-hand column. As a quick reference:

The pattern is broadly geographic: the South and East of England run hard, while most of the North, Scotland, Wales and Northern Ireland are soft and need far less attention.

Cleaning the visible parts

The spout, handle and aerator just need a soft cloth and the same care as any quality tap. Avoid abrasive pads and harsh limescale sprays on the finish, which can dull or pit the coating over time. In hard-water areas the aerator, the mesh at the spout tip, collects scale that weakens the flow. Unscrew it, soak it in a 50/50 mix of white vinegar and water for an hour, rinse, and refit. That single habit keeps the flow strong and is the most common quick fix for a tap that seems to have weakened.

The filter cartridge

On a 4-in-1, the filter is your first line of scale defence as well as what makes the drinking water taste clean. Keep it on schedule: every 6 to 12 months depending on hardness and usage, at roughly £30 to £60 a cartridge. Changing one is usually a tool-free job: turn off the supply to the filter, twist the old cartridge out, twist the new one in, then run a litre or two through to flush it before you drink. A neglected filter does not just taste stale, it lets more scale reach the tank, which brings the bigger descaling job forward. Model your long-term filter spend with the filter cost calculator.

Descaling the tank

> This is the one job not to improvise. The wrong descaling product can damage the heating element or the tank seals. Use your manufacturer's stated procedure and product.

The tank is sealed and insulated, so in soft water it can run for years untouched. In hard water, calcium carbonate precipitates onto the element and tank wall, and an annual descale becomes part of the routine. Most brands publish a simple procedure, and some use a replaceable internal sleeve or anti-scale lining that does much of the work for you. If your tap is under warranty, check whether descaling is something you do yourself or something a service visit covers, because doing it the wrong way can affect a future claim.

Signs your tap needs attention

You do not have to track dates religiously if you watch for the symptoms. Weak or spitting flow usually means a scaled aerator. Drinking water that tastes flat or chlorinated means the filter is overdue. A longer wait for water to come back to full temperature, or a louder reheat than usual, can point to scale on the element and a tank descale due. Any drip from the under-sink unit is worth a prompt look, since seals are a typical wear point later in the tap's life.

When to call a professional

Most maintenance is a homeowner job. Call a professional when the fix is electrical or structural: a tank that will not reheat, a recurring leak from the unit, a pressure-relief valve that keeps weeping, or a heating element that has failed. These tend to appear after year eight to ten and usually mean a part replacement rather than a full tank swap. Replacement elements, seals and cartridge housings can typically be ordered for £60 to £200, with a plumber's call-out on top.

Making it last

Done consistently, this routine is what gets a boiling tap to its 10 to 15 year lifespan with one major service along the way. The brands with the best tank longevity reward the effort most. To see which models hold up best, especially in hard-water regions, read the best taps for hard water round-up, or check your local hardness first on the installers page.