Pipes & water supply

Low water pressure throughout the whole house

Whole-house low pressure usually traces back to the main shutoff valve, a pressure regulator, or supply-side issues, rather than any single fixture.

Difficulty
Moderate
Time
30–60 minutes (diagnosis)
DIY cost
$0–$40
Pro cost
$200–$600

Symptoms

  • Every faucet and shower has weak flow
  • Pressure has gradually decreased over time or dropped suddenly
  • Problem exists at all times of day
  • No single fixture is worse than others

Likely causes

  • CommonMain shutoff valve not fully openA valve accidentally left partially closed after work on the system restricts flow to the entire house.
  • CommonFailing pressure-reducing valve (PRV)This valve regulates incoming pressure and can fail in a way that restricts flow rather than just controlling it.
  • PossibleClogged whole-house sediment filterIf a filter is installed on the main line, a dirty cartridge can significantly reduce flow to the whole house.
  • PossibleCorroded galvanized pipe narrowing the main supply lineOlder homes with galvanized steel pipe can see gradual pressure loss as rust builds up inside over decades.
  • Less commonMunicipal supply issue or well pump problemOccasionally the issue originates before the water even reaches your home's internal plumbing.

What to do

  1. Locate the main shutoff valve (often near where the water line enters the house) and confirm it's fully open.
  2. If you have a pressure-reducing valve, look for a pressure gauge nearby or attach one to an outdoor spigot to read current pressure; below 40 psi is notably low.
  3. Check for and replace a clogged whole-house filter cartridge if one is installed.
  4. Ask neighbors if they're experiencing similar pressure issues, which could point to a municipal supply problem rather than your home.
  5. If on a well, check the pressure tank and pump (see well pump guides) since pump issues affect the whole house similarly.
  6. For suspected old galvanized pipe, a plumber can assess with a pressure test and camera inspection if needed.
  7. If pressure is confirmed low at the meter/main and no clog is found, the PRV itself may need adjustment or replacement by a professional.

Tools and parts

  • Water pressure gauge
Pressure-reducing valve (if replacement needed)Search: “whole house pressure reducing valve”

When to call a pro

Call a plumber if the main valve is fully open, filters are clean, and pressure is still confirmed low, since the PRV or old pipe likely needs professional attention.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.