What Causes Low Water Pressure in a House?
Low water pressure can affect a whole house or just a single tap or shower, and the causes behind each pattern are quite different. A weak trickle from every outlet often points to something affecting the mains supply or the property's internal pipework as a whole, while a single poorly performing fixture is more likely to have a localised cause.
Because pressure problems can stem from anything as simple as a partly closed valve to something as involved as corroded internal pipework, it helps to understand the range of possible causes before assuming the worst. Some issues are quick fixes, while others point to a wider need for central heating or plumbing repairs.
This article covers the most common causes of low water pressure in UK homes, how a plumber narrows down the cause, and what solutions are typically available.
Checking whether it affects the whole house or one outlet
The first useful step is establishing the scope of the problem. If every tap and shower in the house is affected, the cause is more likely to be with the incoming mains supply, the stopcock, or a shared component such as a pressure-reducing valve. If only one tap or shower is weak, the fault is more likely local to that fixture, such as a blocked aerator, a limescale-clogged shower head, or a partially closed isolation valve.
A partly closed stopcock or valve
It sounds simple, but a stopcock or isolation valve that has not been fully reopened after previous work is a surprisingly common cause of reduced pressure throughout a property. Checking that the internal stopcock, usually located under the kitchen sink, is fully open is a quick first check before assuming a more serious fault.
Limescale build-up in pipework and fittings
In hard water areas, which includes much of London and the South East, limescale can build up inside pipework, tap aerators, and shower heads over time, gradually narrowing the space available for water to flow through. This tends to develop slowly, so pressure often decreases gradually rather than suddenly, which can make it easy to miss until it becomes quite pronounced.
Corroded or ageing pipework
Older properties with original galvanised steel pipework can suffer from internal corrosion that narrows the bore of the pipe over decades, reducing flow throughout the system. This is a more significant repair, generally involving replacing sections of pipework, and is more common in period properties that have not had their plumbing updated.
Issues with the mains supply itself
Sometimes low pressure is not caused by anything within the property at all, but by an issue with the water company's mains supply in the area, particularly during periods of high demand or nearby works. If neighbours are experiencing the same issue, it is worth contacting your water supplier before assuming the fault lies within your own pipework.
Problems specific to showers
Electric showers and mixer showers each have their own particular pressure requirements, and a shower that has always run weakly may simply be poorly matched to the property's water system rather than faulty. A plumber can assess whether the shower type is appropriate for your setup, or whether shower repairs or a pump might improve performance.
How a plumber diagnoses low pressure
A visit typically starts with pressure testing at various points in the property to establish whether the issue is general or localised, followed by an inspection of the stopcock, any pressure-reducing valves, and visible pipework. For households across Wimbledon and the surrounding area, our plumbers can carry out this diagnosis and any necessary repairs on the same visit wherever possible, charged at our standard hourly rates.
Need a plumber or heating engineer?
We arrange appointments across Wimbledon and south west London at clear hourly rates. Call 020 3727 2578 or request an appointment.