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How to fix low water pressure

The first question is whether it's one fixture or the whole house. That one answer points you to the right fix, and most of them are free.

Updated · 6 min read

  • DifficultyEasy
  • Time15 minutes–2 hours
  • If you need helpPlumber

Weak water pressure makes every shower and sink chore take longer. The cause can be as simple as a clogged screen the size of a nickel, or as big as a problem with the city's water main. The fastest way to sort it out is to check where the weak flow is happening.

If only one faucet or shower is weak, the problem is almost always at that fixture, and you can fix it in 15 minutes with a bowl of vinegar. If the whole house is weak, look at your valves, your pressure regulator and your water supplier.

What you'll need

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Check: one fixture or the whole house?

  1. Test several faucets. Run cold water at the kitchen sink, a bathroom sink, a tub and an outdoor faucet.
  2. Test hot and cold separately. Note whether only hot water is weak.
  3. Ask a neighbor. If they have weak water too, the issue is likely with your water supplier.

Only one fixture weak? Start with the aerator or showerhead. Everything weak? Skip to whole-house low pressure.

Clean the faucet aerator

The aerator is the small screen screwed onto the tip of the faucet. The East Bay Municipal Utility District explains that sediment flowing through water lines can get trapped in the aerator screen and slow the flow. Hard-water mineral buildup does the same.

  1. Cover the drain. Close the stopper or lay a rag over it so small parts can't fall in.
  2. Unscrew the aerator. Turn it counterclockwise by hand. If it's stuck, wrap pliers in tape and turn gently.
  3. Note the order. Take a photo of how the little screen and washer fit before you take them apart.
  4. Scrub and soak. Brush off debris with a toothbrush. For crusty white buildup, soak the parts in white vinegar, overnight if needed, then scrub again.
  5. Put it back. Reassemble, screw it on hand-tight, and test the flow. If any piece is damaged, replace the whole aerator. Take the old one to the store to match it.

Clean the showerhead

Showerheads clog with minerals the same way. You can usually clean one without taking it down.

  1. Bag it. Fill a zip-top bag with white vinegar and slip it over the showerhead so the face is under the liquid.
  2. Secure it. Wrap a rubber band around the shower arm to hold the bag in place.
  3. Soak. Leave it for a few hours.
  4. Scrub and rinse. Remove the bag, scrub the nozzles with an old toothbrush and run hot water to flush out loosened buildup.

Fix whole-house low pressure

Check for partly closed valves

After any plumbing work, it's common for a valve to be left partly closed.

  1. Find your main shutoff. It's usually where the water line enters the house, in a basement, crawl space, garage or utility closet.
  2. Open it fully. A round wheel handle should be turned counterclockwise until it stops. A lever handle should be parallel to the pipe.
  3. Check the meter valve. If you recently had work done near the meter, the utility side valve may also be partly closed. That one belongs to the water company, so call them rather than turning it yourself.

Check the pressure regulator

Many homes have a pressure reducing valve, a bell-shaped brass part on the main line just after it enters the house. It lowers high street pressure to a safe level. When one fails or is set too low, the whole house gets weak flow.

  1. Test your pressure. Screw a pressure gauge onto an outdoor faucet near where the water comes in, with no other water running, and open the faucet.
  2. Compare. Riverside Public Utilities says residential plumbing and appliances are generally designed to operate between 20 and 80 psi.
  3. Adjust carefully, or call. Riverside notes regulators can be adjusted with the screw and locknut, in small amounts, and that repair kits can be installed by a homeowner or a plumber. If you aren't confident, have a plumber do it.

Call your water utility

If neighbors have the same problem, or pressure dropped suddenly with no work in your home, call your water utility. Main breaks, repairs and high-demand times can all lower pressure. They can also tell you the pressure they deliver to your street. If you're on a private well, low pressure often traces back to the pump or pressure tank, which is a job for a well or plumbing pro.

When to call a pro

Stop and call a plumber if:

  • Your pressure gauge reads below 20 psi or above 80 psi and the utility says their side is fine.
  • You see signs of a leak: damp spots, mold, a running meter with all water off, or a jump in your bill.
  • Only hot water is weak, which points to the water heater.
  • The pressure regulator is leaking, old or you'd rather not adjust it.
  • Your home has old galvanized steel pipes. They can narrow inside over the years, and the fix is usually replacing them.

Renters should report low pressure to the landlord. Not sure what to do? Try the fix it or call a pro quiz.

Keep it from happening again

  • Clean aerators and showerheads a couple of times a year, more if you have hard water.
  • After any work on your street's water lines, clean the aerators on every faucet.
  • Know where your main shutoff is, and check that it's fully open after any plumbing work.
  • Test your pressure once a year with a gauge so you notice changes early.

Common questions

What is normal water pressure for a house?

Residential plumbing and appliances are generally designed to work between 20 and 80 psi, according to Riverside Public Utilities in California. Plumbing codes generally require a pressure regulator when supply pressure goes above 80 psi.

Why is only my hot water pressure low?

If cold water is fine and hot is weak everywhere, the problem is likely at the water heater, such as a partly closed valve or sediment. Check that the valve on the cold inlet pipe is fully open, and call a plumber for anything beyond that.

Can I adjust my pressure regulator myself?

Many regulators have an adjusting screw and locknut, and some utilities say homeowners can make small adjustments. If you're not sure what you have, or the valve is old or leaking, have a plumber do it.

Why did my water pressure drop after the city worked on the lines?

Work on water mains can stir up sediment that gets trapped in faucet aerators and showerheads. Cleaning the aerator screens usually brings the flow back.

Sources

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