What Causes Low Water Pressure?

Low water pressure is frustrating, and the cause can range from a simple fix to something that needs a plumber’s attention — the trick is figuring out whether it’s affecting the whole house or just one fixture.

If it’s just one tap or shower

The problem is likely local: a clogged aerator or showerhead from mineral build-up, a partially closed isolation valve under that specific fixture, or a fault with that tap’s cartridge. These are usually quick, inexpensive fixes.

If it’s the whole house

• A partially closed main stopcock — sometimes knocked during other work
• Pipe corrosion or scale build-up, common in older galvanised steel pipework, which narrows the internal diameter over time
• A hidden leak elsewhere in the system, which reduces the pressure reaching your taps
• Municipal supply issues — worth checking with neighbours or your municipality if the drop happened suddenly and everywhere at once
• A failing pressure pump, if your property relies on one

What to check yourself first

Confirm the main stopcock is fully open, and ask a neighbour if they’re experiencing the same drop — that quickly tells you whether it’s a property issue or a municipal one. If it’s isolated to your property and persistent, it’s worth having the pipework and pressure system properly assessed rather than living with reduced pressure indefinitely, since the underlying cause (corrosion, a leak) tends to get worse over time.