Weak shower? Washer taking forever to fill? Low water pressure has a handful of usual suspects, and a couple of them you can check yourself in five minutes. Here's how we diagnose it — and when it's a sign of something that needs a professional the same week.

First: one fixture, or the whole house?

This single question cuts the problem in half. If it's one faucet or shower, the fix is usually local and cheap. If it's every fixture, look toward the equipment where water enters the house.

If it's one fixture

  • Clogged aerator or shower head. Unscrew it and look for grit and scale. A soak in vinegar often restores it completely. This is the #1 cause we see, and it's a free fix.
  • A partially closed stop valve. The small oval valve under the sink may have been bumped or left half-closed after previous work. Gently open it fully.
  • Only the hot side is weak? That points at the water heater — often sediment buildup. Worth reading our guide to water heater warning signs.

If it's the whole house

  • Failing pressure-reducing valve (PRV). Most homes here have a bell-shaped regulator near the main shutoff. They wear out after 10–15 years, and when they fail, pressure drifts low (or dangerously high). Replacement is a routine visit for us.
  • The main shutoff isn't fully open. After any recent work — water heater swap, remodel, irrigation install — it's worth confirming the main valve got reopened all the way.
  • A hidden leak. Pressure drop plus a water bill that's creeping up, the sound of running water when everything's off, or a soft spot in the yard — stop and call. Finding these early is exactly what our leak diagnostics are for.
  • Aging galvanized pipe. Older homes in the area still have galvanized steel supply lines that close up with corrosion over decades. Pressure that's been slowly declining for years (not weeks) usually points here.

A quick note on pressure vs. flow

True pressure problems and flow problems feel the same at the tap but have different fixes. A $15 gauge on an outdoor spigot tells the real story: healthy household pressure is roughly 45–65 psi. Below 40, think regulator or supply; normal reading but weak fixtures, think blockage. (If you'd rather not fuss with it, we check this first thing on every pressure call.)

When to stop DIYing

Aerators and stop valves are fair game for any homeowner. The moment it involves the PRV, the main line, or a suspected leak, bring in a licensed plumber — those repairs touch the whole house's supply. We'll diagnose it, quote it up front, and beat any reasonable estimate you've already collected.