Why is my water pressure low and how do I fix it?

Low water pressure is annoying, especially when it turns a shower into a trickle. The good news is that in many cases the cause is simple and quick to fix, and in others a plumber can restore proper flow without major work.

Here is how to work out what is going on and when professional help is worth it.

Quick checks you can do yourself

Before calling anyone, run through these easy checks:

• Make sure the stopcock is fully open — it is usually under the kitchen sink or where the supply enters the property.
• Check isolation valves under sinks and toilets are fully open.
• Remove and clean aerators or shower head filters, which can block with scale.
• Try another tap to see if the problem is one fitting or the whole property.

If one tap is affected, the issue is usually that fitting. If every tap is weak, the problem is in the supply or the pipework.

Common causes of low pressure

If the whole property is affected, likely causes include:

• A partly closed or faulty stopcock.
• Scale or debris narrowing the pipework.
• A faulty pressure reducing valve (PRV).
• A combisystem issue, such as low boiler pressure.
• A problem in the shared supply for a flat or block.

When it is the water company

If your neighbours are also affected, or the problem is outside your property, it may be a supply issue that the water company needs to investigate. In that case, contact the water company for your area before arranging plumbing work.

What a plumber can do

If the problem is inside the property, a plumber can identify the exact cause. This might mean adjusting or replacing the PRV, clearing a scale build-up, or resolving a boiler-related issue. In some cases a small booster pump can improve flow to a shower.

If your water pressure is low, our plumbing service can diagnose the cause and restore reliable flow across London.

The Thames Water website has information on supply issues and how to check whether a pressure problem is on their side or yours.