Low Water Pressure Upstairs
- How urgent
- Low risk
- Who fixes it
- A plumber
What's happening?
Pressure drops with height, and a supply that only just copes shows it first on the top floor. In a gravity-fed house the cold tank in the loft feeds the upper floor with only the height of water above the tap, so it is naturally weak upstairs and in the shower. In a mains-fed house the first floor still gets less than the ground floor when the supply is marginal, a stop tap is part-closed, or the pipes are narrow. WaterSafe notes that water companies must supply a pressure that lets water reach the top storey of most homes, measured at your boundary. The whole-house version of this fault is on the low water pressure page.
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What usually causes it?
- A gravity-fed system where the tank sits too low above the upstairs taps
- A stop tap or isolating valve only part-open
- Narrow or partly blocked supply pipework, including old lead or galvanised pipe
- A supply that is marginal at peak times, so the top floor loses out first
- A tank outlet or strainer partly blocked
- A leak on the supply, which drops pressure before it shows anywhere else
- A pressure-reducing valve set low or failing
Is it dangerous?
No. A sudden drop that comes with the sound of running water, damp or a rising meter reading should be checked as a possible leak. Do not fit a booster pump straight onto the mains yourself: the Water Fittings Regulations say a fitting must not harm the pressure of a main, and a pump can starve neighbours.
Can I fix it myself?
Check the stop tap is fully open and back a quarter turn. Compare the kitchen tap with the top-floor tap, and ask whether neighbours are affected. WaterSafe gives a guide: the first tap in the home should fill a 4.5 litre bucket in 30 seconds with everything else off. If the kitchen tap is fine and the top floor weak, the pipework or the tank height is the cause. Descale shower heads and aerators. If you have a loft tank, check it is full and its outlet is clear. Do not add a pump without advice on the type of system you have.
When should you call a plumber?
Call a plumber when the ground-floor flow is good but the top floor is weak, when the tank is gravity-fed, when a pump or accumulator may be needed, when the pressure has dropped suddenly, or when the supply pipe looks old or narrow. Ask your water company if neighbours are affected too.
What will the plumber actually do?
- Test pressure and flow at the stop tap and at the top-floor outlet to separate supply from internal causes
- Check the stop tap, any pressure-reducing valve and the tank outlet
- Find and repair a hidden leak if the readings suggest one
- Replace undersized or blocked pipework on the upper run
- Size and fit a pump, a break tank or an accumulator suited to the system, within the Water Fittings Regulations
Who fixes this
- Low water pressure fix
- Cold water tank replacement
What it usually costs
- Low Water Pressure Pump Cost
- £400–£600
Questions people ask
Why is my water pressure low upstairs but fine downstairs?
What pressure should a water company supply?
Will a shower pump fix low pressure upstairs?
How do I test my water pressure?
Sources & References
Before you book, read what to check before a plumber starts.
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