ROUGHPLUMB PLUMBING GUIDE

Why Is My Water Pressure Low?

Quick answer

First determine whether the problem affects one fixture, several fixtures, or the entire house. That single distinction greatly narrows the likely cause.

First thing to determine

Compare hot and cold flow at more than one fixture. Then decide whether the weakness is isolated to one outlet, one branch/area, or the whole building.

Common causes

  • Clogged aerator or fixture restriction
  • Partially closed or failed fixture shutoff
  • Kinked or restricted supply connector
  • Whole-house filter restriction
  • Main shutoff not fully open or malfunctioning
  • Pressure reducing valve problem where one is installed
  • Municipal supply or building-wide pressure issue

What to check

  • Remove and inspect an accessible faucet aerator where appropriate
  • Compare hot and cold at the affected fixture
  • Check another fixture on a different branch
  • Confirm accessible main valves appear fully open without forcing them
  • Check serviceable whole-house filters for restriction or overdue maintenance

What not to do

Do not adjust a pressure-reducing valve blindly. First establish whether the issue is actually whole-house pressure rather than a fixture restriction.

ROUGHPLUMB KNOWLEDGE JOURNEY

Why Is My Water Pressure Low?

START HERELow Water Pressure in HouseUNDERSTAND NEXTMain Water Shutoff ValveUNDERSTAND NEXTPressure-Reducing Valve (PRV)UNDERSTAND NEXTHow to Check House Water PressureUNDERSTAND NEXTFaucet Aerator
VISUAL LIBRARY

See the plumbing involved

PartMain Water Shutoff ValveKnow what the main shutoff looks like and why every homeowner should locate it before an emergency.View visual guide PartPressure-Reducing Valve (PRV)Identify a PRV and understand its role in controlling downstream water pressure.View visual guide MeasurementHow to Check House Water PressureUse a suitable pressure gauge and a full-flow test point to establish a useful baseline.View visual guide PartFaucet AeratorA small restriction at the aerator can make one faucet look like a whole-house pressure problem.View visual guide
TRADE TIP

A pressure gauge at a suitable full-flow source can help separate true supply-pressure problems from fixture-specific flow restrictions.

When to call a plumber

Call a plumber when the whole house is affected, the main valve or PRV is suspect, pressure changes suddenly without explanation, or piping restrictions are likely.

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