Why is my shower pressure weak?
Start with the shower head, because it is the cause more often than the system is.
- Difficulty
- beginner
- Time
- 40 min
- Read
- 3 min
- Safety
- caution
Short answer
Unscrew the shower head and soak it in descaler overnight. Limescale blocking the holes is by far the most common cause, and it costs nothing to rule out before looking at anything else.
Poor shower pressure has an obvious expensive explanation and a much more likely cheap one. Working from the cheap end saves most people a plumber's visit.
Safety
Step by step
- Descale the shower head first.Unscrew it, soak it overnight in descaler or white vinegar, and poke the holes through. In a hard water area this is the answer most of the time and it costs nothing to try.
- Check the hose and the filter.Flexible hoses kink and collapse internally. Many mixer showers have a small filter washer where the hose meets the valve — it clogs with grit and is easily missed.
- Compare it with the taps.If everything in the house is weak, it is the supply rather than the shower. If only the shower is weak, it is the shower. This single comparison narrows it immediately.
- Check hot and cold separately.Run each side alone if the valve allows. Weak on one side only points at that supply — often a partly closed isolation valve or a blocked filter.
- Find out what type of system you have.Combi boiler: pressure comes from the mains, so mains pressure is the limit. Gravity-fed with a tank in the loft: pressure comes from the height of the tank, and it is naturally low upstairs.
- Check the isolation valves.Small screwdriver-slot valves in the pipework to the shower. Left partly closed after previous work, which is common. The slot should run in line with the pipe.
- Consider a pump only for gravity systems.A shower pump can transform a gravity-fed system. It does nothing on a combi or unvented system, where the mains is the constraint — fitting one there is wasted money.
- Get the mains pressure checked if everything is weak.A plumber can measure it, and the water company has a minimum pressure obligation at the boundary. Worth establishing before spending anything.
Tips
- Descale the shower head every six months in a hard water area. It prevents the problem entirely and takes ten minutes.
- Water-saving heads restrict flow deliberately. If a new head made things worse, that is why.
- An electric shower's output depends on its kilowatt rating, and it is always weaker in winter because the incoming water is colder.
If it doesn't work
Only the shower is weak
Cause: Blocked head, hose or filter — Fix: Descale the head, check the hose for kinks and clean the filter washer.
Everything in the house is weak
Cause: Mains pressure or a partly closed stopcock — Fix: Check both stopcocks are fully open, then ask the water company to check pressure.
Weak upstairs only
Cause: Gravity-fed system with low tank height — Fix: A shower pump is the usual answer for a gravity system.
Got worse suddenly
Cause: Debris after work on the pipes, or a failing part — Fix: Clean all filters — work on the mains dislodges grit that lands in the nearest filter.
Questions people ask
Why is my shower weak but the taps are fine?
Almost always the shower head or hose rather than the system. Descale the head and check the filter washer where the hose connects.
Will a shower pump fix it?
Only on a gravity-fed system with a tank in the loft. On a combi or unvented system the mains is the limit and a pump will not help.