Published: Thursday 26th June, 2025

Why Is My Water Pressure So Low? 9 Common Causes and Fixes

We know it’s a pain. Weak showers, slow-filling washing machines, and taps that barely trickle can make everyday tasks more frustrating than they need to be.

Low water pressure can happen for all sorts of reasons. Sometimes it’s an issue with your plumbing, other times it’s down to the mains supply or the way your home’s water system is set up. In this guide, we’ll walk you through 9 of the most common causes of low water pressure in UK homes — and what you can do about them.

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1. Your internal stop tap isn’t fully open

A good place to start is your internal stop tap, which is usually located under the kitchen sink. This tap controls the flow of mains water into your home. If it’s even slightly closed, it can restrict water pressure throughout the house.

???? What to do:
Turn the tap fully clockwise to close it, then back anti-clockwise until it’s fully open. Make sure it’s as open as it will go without forcing it.

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2. The external stop tap is partially closed or faulty

There’s also an external stop tap (often in the pavement outside your home) that’s controlled by your water supplier. If recent work has taken place nearby, or the valve hasn’t been properly reopened, it can result in low pressure indoors.

???? What to do:
Contact your water supplier and ask them to check the external valve and test the incoming mains pressure at your boundary. They may be able to resolve the issue quickly.

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3. Limescale or corrosion in your pipework

Over time, mineral build-up or rust inside older pipework can reduce the internal diameter of the pipes, limiting water flow. This is especially common in areas with hard water or in homes with original pipework.

???? What to do:
A qualified plumber can assess whether the pipes are partially blocked and advise on possible solutions. In some cases, a system flush may help; in others, replacing the affected sections of pipework may be necessary.

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4. One tap or fitting is faulty

If only one tap or shower seems to be affected, the issue could lie with the fitting itself. Common causes include blocked aerators, limescale in the showerhead, or worn internal parts like cartridges or washers.

???? What to do:
Clean the fitting by soaking it in white vinegar to remove limescale. If the issue persists, replacing the tap or showerhead may restore normal pressure.

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5. Your plumbing system is gravity-fed

Many older UK homes still rely on gravity-fed systems, where water is supplied from a cold water tank in the loft and a hot water cylinder in the airing cupboard. These systems rely on the height difference between the tank and the outlet to create pressure — which means upstairs showers and taps often suffer from weak flow.

???? What to do:
Installing a booster pump for key outlets (like a shower) can improve flow. Alternatively, switching to a combi or system boiler may provide better mains-fed pressure throughout the home.

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6. There’s an issue with your boiler or unvented hot water system

Combi boilers and unvented hot water cylinders rely on the mains supply to deliver pressure. If the incoming pressure is low, or if components like pressure-reducing valves (PRVs) are faulty or incorrectly set, hot water pressure can be noticeably affected.

???? What to do:
A Gas Safe registered engineer or plumber can check the flow rate and system components to identify any faults or restrictions.

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7. There may be a hidden leak

Leaks in your plumbing system — especially ones that go unnoticed under floors or behind walls — can significantly reduce water pressure. Signs include sudden drops in pressure, higher-than-normal water bills, or damp areas on walls, ceilings, or floors.

???? What to do:
To check for a leak, turn off all taps and appliances, then see if your water meter is still moving. If it is, you may have a leak and should contact a plumber for leak detection and repair.

If you're unsure, read our guide to 5 signs that you may have a water leak— it’s full of practical tips to help you spot the warning signs early.

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8. Mains water pressure in your area is too low

Sometimes the issue isn’t inside your home — it’s with the mains water supply. If your neighbours are also experiencing low pressure, there may be a wider problem with the local network.

UK water suppliers are legally required to provide a minimum pressure of 1 bar at the boundary of your property. Anything below that may be their responsibility to fix.

???? What to do:
Check with neighbours to see if they’re experiencing the same issue. Then contact your water supplier and request a pressure test. If the supply is below the legal minimum, they should take action to resolve it.

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9. You’re on a shared supply or experiencing high demand

In some cases — especially in older terraced houses or rural areas — properties share a single mains pipe. If multiple homes are using water at the same time, your pressure may drop, particularly during busy times like early mornings or evenings. High demand in general (e.g. during heatwaves) can also reduce pressure across an area.

???? What to do:
If the problem is ongoing, consider installing a booster pump and accumulator tank to store water and boost pressure inside your home. This can make a big difference, especially for upstairs bathrooms or high-pressure appliances.

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How to check your water pressure at home

Here’s a quick way to check whether your water pressure might be on the low side:

1. Turn off all taps and appliances that use water.
2. Fill a 1-litre jug from your kitchen cold tap (this tap is usually mains-fed).
3. Time how long it takes to fill.

• Less than 6 seconds = Normal pressure (around 10 litres per minute or more)
• 6–10 seconds = Borderline pressure
• More than 10 seconds = Low pressure (under 6 litres per minute)

This simple check can also be useful when viewing a new home. Low water pressure isn’t always obvious during a short viewing, so taking a minute to test the flow at the kitchen tap could save you a headache later on.  For more practical tips on what to look for when viewing a property, read our guide: 10 things estate agents say you should always check on a home viewing.

For an accurate reading, a plumber can use a proper pressure gauge at your internal stop tap.

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Final thoughts

Low water pressure isn’t something you have to put up with. In many cases, it’s easy to identify the cause once you know what to look for — whether it’s a closed valve, a faulty tap, or an issue with the mains supply.

If you’ve gone through the common causes and still aren’t sure what’s wrong, getting professional advice is the next best step. A qualified plumber or heating engineer will be able to test your pressure, inspect your system, and recommend a solution that fits your home and budget.