What water pressure is too high for a house?

There is no single legal limit on incoming pressure, but the practical answer is that the weak components in a domestic system are flexible hoses, fill valves and appliance inlet valves rather than the pipework. If you are seeing water hammer, spraying taps or repeated hose failures, the pressure is too high for your fittings regardless of the number on the gauge. A reducing valve set around three bar removes the problem.

Can high water pressure cause a leak?

Yes, and it is one of the more common underlying causes. It fails flexible hoses, works compression joints loose over time through water hammer, and stops toilet fill valves seating properly. The leak gets fixed and the cause does not, so it recurs elsewhere.

Will a pressure reducing valve ruin my shower?

Not if it is set sensibly. It limits static pressure rather than flow rate, and most showers are perfectly happy at three bar. What you lose is the peak overnight pressure that was damaging the fittings.

Why is my water pressure higher at night?

Because less is being drawn from the main across the area, so less is lost to friction and the static pressure at your property rises. It is also why hoses tend to burst overnight rather than during the day.

My water pressure seems too high

What high pressure actually looks like

People rarely measure it. They notice the symptoms, and the symptoms are consistent: taps that spray rather than pour and splash out of the basin, a bang in the pipework when a tap or the washing machine shuts off, a toilet fill valve that hisses and will not quite close, and flexible hoses under sinks that fail more than once in a few years. The last one is why this sits on a leak site.

Do this first

Measure it rather than guess. A pressure gauge that screws onto a washing machine tap or an outside tap costs very little. Read it with everything closed, and again with a tap running. The first number is static pressure and it is the one that stresses fittings, and it is usually highest overnight when demand on the main is low.
Check whether you already have a pressure reducing valve. There is often one just after the stopcock. They fail, and they fail open, so a system that used to be fine and is now hammering may simply have a dead valve rather than a changed supply.
If a flexible hose has already burst once, replace the rest. They are the weakest part of a domestic system and they age together. Use hoses carrying a recognised approval mark rather than the cheapest available.
Do not simply close the stopcock part way to calm it down. That throttles flow without properly controlling static pressure, and it leaves you with a stopcock you can no longer trust in an emergency.

What is normal

London mains pressure commonly sits somewhere around two to five bar and varies with your height relative to the local reservoir, the time of day and how much the rest of the street is drawing. There is a statutory minimum a supplier has to maintain at your boundary, but there is no equivalent statutory maximum on what arrives, which is why properties at the bottom of a hill can sit permanently high. Copper and properly made joints tolerate it. Flexible hoses, fill valves, appliance inlet valves and cheap mixer cartridges are what give way.

The fix

A pressure reducing valve on the incoming main, fitted after the stopcock and somewhere it can be reached, typically set around three bar. It is a small job and it protects every fitting downstream.

Two things are worth getting right when it goes in. It needs to be accessible for adjustment and future replacement, not buried behind a fitted unit. And on a system with an unvented cylinder, fitting a reducing valve changes how the system behaves when the water expands, so the existing expansion arrangement has to be checked rather than assumed. Work on the supply is covered by the Water Supply (Water Fittings) Regulations 1999, which is a good reason to have it done by someone working to them.

Why a pressure page is on a leak site

The burst flexible hose under a kitchen or bathroom unit is one of the most common escape-of-water claims there is, and it happens while nobody is home because static pressure peaks overnight. The hose is the thing that failed; the pressure is the reason it failed. Replacing the hose and leaving the pressure alone buys you a few years until the next one.

Frequently asked

What water pressure is too high for a house?: There is no single legal limit on incoming pressure, but the practical answer is that the weak components in a domestic system are flexible hoses, fill valves and appliance inlet valves rather than the pipework. If you are seeing water hammer, spraying taps or repeated hose failures, the pressure is too high for your fittings regardless of the number on the gauge. A reducing valve set around three bar removes the problem.
Can high water pressure cause a leak?: Yes, and it is one of the more common underlying causes. It fails flexible hoses, works compression joints loose over time through water hammer, and stops toilet fill valves seating properly. The leak gets fixed and the cause does not, so it recurs elsewhere.
Will a pressure reducing valve ruin my shower?: Not if it is set sensibly. It limits static pressure rather than flow rate, and most showers are perfectly happy at three bar. What you lose is the peak overnight pressure that was damaging the fittings.
Why is my water pressure higher at night?: Because less is being drawn from the main across the area, so less is lost to friction and the static pressure at your property rises. It is also why hoses tend to burst overnight rather than during the day.

No find, no fee · £150 per hour. The rate is fixed before we attend and does not rise for a difficult property, an awkward access or an evening visit. The total depends on how long the job takes; the rate cannot change.