A sudden drop in water pressure is often caused by something outside your property, such as repairs or a burst on the water main, but it can also be caused by a partly closed stopcock, a leak, or debris disturbed during recent plumbing work. Checking whether neighbours are affected is a good first step.
A sudden change usually has a different cause from a slow decline over months, so when it started is a useful clue. It also helps to know whether the drop affects every tap or just some.
Problems Outside Your Property
Water companies carry out repairs and maintenance on their network, and a burst main can affect several homes at once. If your neighbours have also noticed a drop, the cause is more likely to be on the public supply. Your water supplier may have information about planned work or known problems in your area.
Wessex Water explains that the water company looks after the mains and the pipe up to the edge of the street, while the supply pipe on your land is usually the property owner’s responsibility. Other suppliers may describe this slightly differently, so it is worth checking with your own.
A Valve That Has Been Turned
If work has recently been done in the property, the stopcock or another valve may not have been fully reopened. A partly closed stopcock can noticeably reduce the water reaching your taps.
The same can happen with isolating valves on the pipes to individual taps, toilets or appliances, which may explain a drop in just one area.
Check whether the stopcock is fully open by turning it gently anticlockwise. If it is stiff, do not force it, as this could damage the valve.
Leaks, Frozen Pipes and Debris
A leak on the supply pipe or inside the property can reduce the water reaching your taps. Signs may include damp patches, the sound of running water or a water meter that keeps moving when nothing is on. A drop in pressure does not prove there is a leak, though.
In cold weather, a frozen pipe can reduce or stop the flow. Debris disturbed during work on the mains or your own plumbing can also collect in valves, filters or tap aerators. If you suspect a leak, our leak detection page explains how hidden leaks are investigated.
What to Do Next
Note when the drop started, whether it affects hot, cold or both, and which taps are affected. If only one tap is weak, the cause may be in that tap. If everything is affected and neighbours are fine, the problem may be within your property.
Our page on water pressure problems in Poole explains how sudden and ongoing pressure problems are assessed.
If your water pressure has dropped suddenly and the cause is not clear, a plumber can help narrow down whether the problem is inside your property.