Low water pressure is one of those problems that's easy to live with and easy to ignore — until you try to shower properly or fill a bath in under 20 minutes. Here's what's behind it and what the options are.
First: is it your supply or your system?
The fix depends on where the problem starts. Low pressure is either coming in from the mains (a supply issue) or being caused by something inside your home (a system issue).
Quick test: Check if the pressure is low on both hot and cold, and at every tap. If it's low everywhere — mains supply is likely the cause. If it's only low on certain taps or only hot water — the problem is inside your property.
Causes — mains supply
You're in a low-pressure area
Some areas have naturally lower mains pressure than others, particularly in older residential streets or at the end of long supply runs. Hemel Hempstead's newer developments tend to have better pressure than some of the older parts of town.
Fix: Your water supplier sets the mains pressure and it's their responsibility if it falls below the minimum standard (1 bar at the boundary). Call them and ask them to test it. If it's below standard, they're required to address it.
Shared supply pipe
Older terraced or semi-detached houses sometimes share a supply pipe with neighbouring properties. When neighbours are using water simultaneously, pressure drops.
Fix: A dedicated supply pipe from the mains — this involves a plumber and potentially the water authority, but it's a permanent solution.
Causes — inside your home
Partially closed stopcock
Your main stopcock (usually under the kitchen sink) may not be fully open. It's worth checking — they sometimes get accidentally turned during work under the sink.
Fix: Turn it fully anti-clockwise. Takes 10 seconds.
Limescale in pipes or fittings
In hard water areas like Hemel Hempstead, limescale builds up inside pipes and fittings over time, gradually restricting flow. It's particularly common in older copper pipework.
Fix: Descaling, or in severe cases, replacing the affected pipe sections or fittings.
Faulty pressure reducing valve (PRV)
Some properties have a pressure reducing valve fitted to protect the internal system from high mains pressure. If this fails or is set too low, it reduces flow throughout the house.
Fix: The PRV needs adjusting or replacing — straightforward for a plumber.
Low hot water pressure only
If the low pressure is only on hot water, the issue is usually with the hot water system itself — a blocked filter on the hot water outlet, a failing pump (on pressurised systems), or scale in the hot water cylinder.
What won't fix it
- Changing your shower head (can improve flow feel but doesn't fix underlying pressure)
- Booster pumps (can help symptoms but won't fix a shared supply pipe or a failing PRV)
When to call a plumber
Call a plumber if:
- The pressure has dropped suddenly (possible leak or burst)
- It's low throughout the whole house and the stopcock is fully open
- You've had low hot water pressure that's getting gradually worse
- You want a proper diagnosis before spending money on a fix
If you're dealing with low water pressure in Hemel Hempstead, Ealing, or NW London — get in touch. We'll find where the problem actually is before recommending anything.