How to Fix Low Water Pressure

Diagnosing the Problem

First establish: is low pressure affecting one tap or fitting, or the whole house? One tap: likely a blocked aerator, partially closed isolator valve, or scale buildup. All hot water: likely the boiler or hot water cylinder. All water throughout: check the mains stopcock is fully open.

Fix 1 — Clean the Aerator

The aerator is the small mesh screen at the tip of the tap. Unscrew it, soak in white vinegar for 30 minutes to dissolve limescale, rinse, and refit. This simple fix restores full flow to many taps in hard water areas.

Fix 2 — Check Isolation Valves

Isolation valves under sinks and toilets are sometimes partially closed after maintenance work. Check that the slot on the valve head is parallel to the pipe (open). A slot perpendicular to the pipe means the valve is closed.

Fix 3 — Descale Shower Head

Shower heads in hard water areas clog with limescale quickly. Remove the shower head, soak in white vinegar overnight, and scrub the nozzles with an old toothbrush. This restores flow in most cases.

Fix 4 — Check the Mains Stopcock

The mains stopcock (usually under the kitchen sink) must be fully open. Turn anticlockwise until it stops. Old stopcocks can jam partially open over time — a plumber can replace a faulty stopcock.

When to Contact Your Water Supplier

If low pressure affects multiple properties in your street, it is a water company issue. Contact your water supplier to report it. They have a statutory duty to maintain minimum supply pressure.