Weak showers, slow-filling tubs and a dishwasher that takes forever all point to low water pressure. Before you live with it, figure out whether it's one fixture or the whole house — that tells you a lot about the cause.
Is it one fixture or the whole house?
If only one faucet or shower is weak, the problem is almost always at that fixture. If every tap is weak, the issue is in the main line, the pressure regulator, the pipes, or the water supply itself.
8 common causes of low water pressure
1. Clogged aerators and shower heads
Hard water in many parts of California leaves mineral scale in aerators and shower heads. Unscrew them, soak in vinegar and rinse. If flow returns, that was it. See our faucet repair page if the cartridge is the problem.
2. A failing pressure regulator (PRV)
Many homes have a bell-shaped pressure reducing valve where the main line enters. When it fails, pressure can drop suddenly. A plumber can test pressure with a gauge and replace the PRV.
3. Partially closed shutoff valves
After any plumbing work, check that the main shutoff and the valve at the meter are fully open.
4. Corroded galvanized pipes
Galvanized steel pipe rusts from the inside, narrowing until little water gets through. Older homes often need a whole house repipe to restore pressure for good.
5. A hidden leak
Water escaping from a broken pipe isn't reaching your fixtures. If your water bill is up too, call for leak detection or slab leak detection.
6. A damaged main water line
A crushed or leaking service line between the meter and the house reduces flow to everything. Our water line repair team can locate and replace it.
7. Water heater issues (hot side only)
If only hot water is weak, sediment in the water heater or a partly closed valve may be the cause.
8. Utility supply problems
Ask neighbors. If everyone has low pressure, contact your water provider.
When to call a plumber
Call if pressure dropped suddenly, if it's low everywhere, or if you also notice discolored water or a higher bill. Our plumbers test pressure, check the regulator and track down leaks across California — including San Jose, Long Beach and Fresno.
FAQs
What is normal household water pressure?
Most homes run best between about 40 and 80 psi.
Why did my water pressure suddenly drop?
Sudden drops are often a failed pressure regulator, a main-line leak or utility work.
Will repiping fix low water pressure?
If corroded galvanized pipe is the cause, yes.