Why is my water pressure low?

Questions about low water pressure

Why is my water pressure suddenly low?

A sudden drop in water pressure is usually caused by one of four things: a partially closed stopcock or isolation valve somewhere in the system, a leak in the supply pipe or internal pipework, a fault in the water meter, or a wider mains supply issue affecting your street or area. If the drop is sudden and affects the whole house, check your main stopcock first - it is usually under the kitchen sink or near the front door - and make sure it is fully open. If neighbouring properties are also affected, contact your water supplier.

Why do I have good pressure downstairs but low pressure upstairs?

Pressure naturally drops over height. If your home has a gravity-fed hot water system - which uses a cold water tank in the loft rather than drawing directly from the mains - upstairs outlets will always have lower pressure than downstairs ones. The water falls from the tank under gravity, so the shorter the drop, the lower the pressure. Fitting a pump on a gravity-fed system or upgrading to a mains-pressure unvented cylinder are the two main solutions. If your system is mains-fed throughout and pressure is still low upstairs only, a blockage or partially closed valve is more likely.

Why do I only have low pressure on the hot water?

Low pressure only on hot water usually points to the hot water system specifically, not the mains supply. The most common causes are a build-up of limescale or debris in the hot water cylinder or its associated pipework, a faulty pressure-reducing valve, an airlock in the hot water circuit, or a failing pump on a gravity-fed system. If your hot water pressure drops further when several outlets are running at the same time, it is often a sign of an undersized system struggling with simultaneous demand.

Could a leak be causing low water pressure?

Yes. A significant leak in the supply pipe between the water meter and your property can reduce the pressure entering your home. Signs include an unexplained increase in your water bill, damp patches in the garden or along the pavement outside, and persistent low pressure that cannot be explained by the property's plumbing system. You can check for a leak by turning off all water in the property and watching your water meter: if it continues to move, there is likely a leak on the supply side. Contact your water supplier or a plumber.

What is the normal water pressure for a UK home?

Water companies in the UK are required to maintain a minimum mains pressure of one bar at the point where the supply pipe enters your property. Most properties receive between one and three bar. Combi boilers and unvented cylinders typically require a minimum incoming pressure of one to one and a half bar to operate correctly. Anything below one bar at the incoming supply is grounds for your water supplier to investigate. Internally, gravity-fed systems can deliver well below one bar at the outlet - particularly upstairs - which is why pumped or pressurised systems are now more common in new builds.