Low Water Pressure in the House: What Causes It and What to Do

Low water pressure in the house has very different causes depending on whether it affects one fixture or all of them. Start by working out which.

One faucet or shower only

Unscrew the aerator or shower head and look for grit and scale. Clean or replace it. If flow is still weak, the cartridge is likely clogged, which is a faucet repair or shower repair.

Hot water only

Weak hot water at every fixture points to the water heater: sediment, a partly closed valve or a failing dip tube. That is a water heater repair call.

The whole house

• Partly closed main valve. Check the valve at the meter and the one where the line enters the house.
• Failing pressure regulator. Many homes have a bell-shaped regulator near the main. They wear out after 10 to 15 years.
• Galvanized pipe. Steel pipe rusts from the inside until only a pencil-sized opening is left. Common in homes built before the 1960s. The fix is repiping.
• A leak. A hidden leak or a leaking service line steals pressure. Check the meter with all water off, then book leak detection.
• A failing water service line. See water line repair.

Ask the neighbors

If the whole street is affected, the water utility is probably working on a main. If it is only your house, the cause is on your side of the meter.

When to call

Sudden pressure loss across the house can mean a burst pipe. Shut off the water and call an emergency plumber. For gradual loss, a plumbing inspection with a pressure test finds the cause.

Common questions