Improve low water pressure in the house

Find out why your water pressure is low, fix common causes yourself, and know when to call your water supplier.

WP-01Work out if it's one tap or the whole houseTest the cold tap in the kitchen, then bathroom taps and the shower, one at a time. If only one outlet is weak, the problem is local to that fitting. If every tap is weak, the problem is likely at the stopcock, the mains supply, or a storage tank if you have one.

WP-02Check your stopcock is fully openFind your internal stopcock, usually under the kitchen sink or where the supply pipe enters the house. Turn it fully anticlockwise to open it fully; it's easy for it to get left part-closed after other work. If you have an outside stopcock near the boundary, check that one too.

WP-03Check isolation valves at sinks, toilets and appliancesLook under sinks, behind toilets, and at the washing machine and dishwasher for small lever or slotted valves on the supply pipe. Make sure each one is turned fully in line with the pipe, not part-way across. These are often left part-closed after a repair and forgotten.

WP-04Clean limescale from the affected tap or shower headUnscrew the aerator from the tap, or the shower head, and check for a build-up of white scale, especially in hard-water areas. Soak the part in descaler or white vinegar for a few hours, then scrub with an old toothbrush and rinse well. Refit and test the flow.

1 bottle · Limescale descaler or white vinegar

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1 each · Old toothbrush

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WP-05Rule out a hidden leakA leak elsewhere in the system can starve the rest of the house. Turn off every tap, note your water meter reading, wait 30 minutes, then check it again. If the reading has moved, you have a leak somewhere in the pipework. Also check for damp patches under floors or near visible pipework.

RULES

KNOW THE RULES

Under the Water Industry Act 1991, you're responsible for the supply pipe from the boundary of your property to the house. If the leak is on that section, it's yours to fix, not the water company's.

WP-06Check the cold water storage tank, if you have oneIn older houses with a tank in the loft, check the float valve moves freely and the tank fills to its normal level. A stuck float valve, a blocked filter, or a low water level in the tank will reduce pressure at upstairs taps and showers fed from it.

WP-07Check your boiler pressure if you have a combi boilerA combi boiler's pressure gauge should normally read between 1 and 1.5 bar when cold. If it's below 1 bar, hot water flow will be weak even if cold taps are fine. Top it up using the filling loop following the maker's instructions. If you're not confident, or the pressure keeps dropping, call a Gas Safe registered engineer.

RULES

KNOW THE RULES

By law, only a Gas Safe registered engineer can work on the gas parts of a boiler. Topping up water pressure via the filling loop is fine to do yourself.

WP-08Contact your water supplier if the whole house is affectedIf every tap is weak, there's no leak, and the stopcock and valves are all fully open, check your water company's website for known issues in your area first. If nothing is reported, contact them directly, as they must maintain a minimum pressure at your property boundary.

RULES

KNOW THE RULES

Water companies must meet a guaranteed minimum pressure standard at the boundary stopcock, typically equivalent to a 10m head (about 1 bar). If they're below this, you may be entitled to compensation.

WP-09Get permission before fitting a booster pumpIf mains pressure is confirmed as genuinely low, a booster pump can help, but you must not connect one directly to the mains supply without your water supplier's consent. Some pumps need a break tank fitted first. Contact your supplier, then get quotes from a plumber once you have written consent.

RULES

KNOW THE RULES

Under the Water Supply (Water Fittings) Regulations 1999, you need your water supplier's permission before fitting a pump to boost mains pressure.

WP-10Tidy up and check your workRefit any aerators or shower heads, make sure every valve you touched is left fully open, and dry any pipework you worked on. Run each tap for a minute to clear any loosened debris, then check for drips at fittings you disturbed. Note the date, so you can tell later if the fix has held.

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