Low water pressure in shower
Poor shower pressure is one of the most common plumbing complaints in the UK. The cause varies depending on whether you have a combi boiler, gravity-fed system, or pressurised cylinder. This guide walks through the most common causes and what you can do about each one.
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Most likely cause & what to check
Identify your system — if you have a combi boiler, pressure comes straight from the mains. If you have a cold water tank in the loft, you have a gravity-fed system. Gravity systems are naturally lower pressure, especially in ground floor showers.
For combi systems: check the boiler pressure (should be 1–1.5 bar). Low boiler pressure directly reduces shower flow. Repressurise using the filling loop if needed.
Check the shower head — unscrew it and look for limescale build-up in the filter and nozzles. Soak in white vinegar for 30–60 minutes and scrub clean.
Check the shower valve — the flow restrictor inside many thermostatic valves can become clogged. Refer to the valve manufacturer's guide to locate and clean or remove the restrictor.
Check isolation valves on the hot and cold supplies to the shower — make sure both are fully open.
For gravity-fed systems: fitting a shower pump is the most effective long-term fix. These boost pressure specifically for the shower and are fitted by a plumber.
If pressure has recently dropped and nothing has changed, check whether other taps in the house are also affected — a supply issue with the mains may need reporting to your water supplier.
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Frequently asked questions
Will fitting a pump void my boiler warranty?
A pump is for gravity-fed systems only — it would not be fitted alongside a combi boiler. For combi systems, the mains pressure is what drives the shower.
How much does a shower pump cost to install?
A twin-impeller shower pump costs £100–£200 for the unit, plus £100–£200 for installation, depending on accessibility.