Check your main water shut-off valve first

The fastest fix for low water pressure is often the simplest: your main shut-off valve may be partially closed. This valve controls all water entering your home and sits where the water line comes in from the street — usually in a basement, crawl space, or outside in a box near your foundation. If someone turned it partway closed during repairs or maintenance, your pressure drops when ready.

Turn the valve handle counterclockwise until it stops. If it was already fully open, move to the next step. If it was partially closed, you should feel pressure increase within seconds. Mark the valve's position so you know what fully open looks like, and check it every few months — valves can drift closed over time.

Key Takeaways

  • Your main shut-off valve controls water pressure to the entire house; a partially closed valve is the most common cause of low pressure and takes seconds to fix.
  • Mineral buildup in aerators and showerheads reduces flow; removing and cleaning them often restores pressure without replacing anything.
  • A pressure regulator that has failed or is set too low can be adjusted or replaced, usually for under $100 in parts.
  • Leaks in supply lines waste pressure; if pressure is low everywhere in the house, check for wet spots in walls, ceilings, or under sinks.
  • If pressure is low in only one room or fixture, the problem is local to that line and does not require whole-house repairs.

Clean aerators and showerheads to remove mineral deposits

Mineral buildup inside faucet aerators and showerheads narrows the opening and reduces flow. This happens faster in areas with hard water. Cleaning takes five minutes and costs nothing.

Unscrew the aerator (the small screen at the faucet tip) by hand or with pliers wrapped in a cloth to avoid scratching. Soak it in white vinegar for 30 minutes to dissolve mineral deposits, then scrub with an old toothbrush and rinse. Screw it back on. Do the same for showerheads — unscrew, soak, scrub, rinse. If pressure improves noticeably, the problem was local to those fixtures. If pressure is still low everywhere, move to the next step.

Inspect your pressure regulator and adjust or replace it

Most homes have a pressure regulator — a bell-shaped device on the main water line that keeps pressure from getting too high and damaging pipes. If it fails or is set too low, your pressure drops throughout the house. You can usually see it near the main shut-off valve.

A regulator has a screw on top. Turn it clockwise (very slowly) to increase pressure, then test a faucet. Stop when pressure feels normal — usually between 50 and 80 pounds per square inch. If turning the screw does nothing, the regulator has failed internally and needs replacement. A new one costs $20 to $60 in parts, and installation takes 20 to 30 minutes if you are comfortable with basic plumbing. If you are not, a plumber charges $150 to $300 for the job.

Look for leaks in supply lines

A leak in your water supply line wastes pressure before it reaches your fixtures. If pressure is low everywhere in the house, check for wet spots in your basement, crawl space, or under sinks. Look for water stains on ceilings or walls, soft spots in drywall, or unexplained puddles.

If you find a leak, you will need a plumber to locate and repair it — the cost depends on where the leak is and how accessible it is. Supply lines run inside walls and under floors, so a leak in those spaces may require cutting into walls or flooring. Get a quote before committing. If you find no visible leaks, the problem may be in a line you cannot see, and a plumber can use a pressure test to confirm.

Identify whether the problem is local or whole-house

Before calling a plumber, determine whether low pressure affects your entire home or just one room or fixture. Turn on a faucet in the kitchen, then one in a bathroom upstairs, then a shower. If all have low pressure, the problem is in your main line or regulator. If only one fixture has low pressure, the problem is in that line alone and usually costs less to fix.

A single low-pressure fixture often means a clogged aerator (which you already cleaned), a closed shut-off valve under that sink, or a failing valve inside the fixture itself. Check under the sink for a small valve and make sure it is fully open. If it is, the fixture may need replacement or internal repair.

When to call a plumber

Call a plumber if pressure remains low after you have cleaned aerators, checked the main shut-off valve, and adjusted the regulator. Also call if you find signs of a leak or if pressure is low in only one fixture and the shut-off valve under it is already open.

A plumber can test your water pressure with a gauge (a $10 tool you can also buy yourself), run a pressure test on your lines to find leaks, and replace a failed regulator or valve. Expect to pay $100 to $200 for a service call and diagnosis, plus the cost of any repairs. Getting a quote over the phone before the visit can help you decide whether to proceed.

Frequently Asked Questions

Can low water pressure damage my pipes?

Low pressure itself does not damage pipes, but the underlying cause might. A leak in your supply line wastes water and can rot wood framing or drywall if it goes unrepaired. A failed pressure regulator can allow pressure to spike, which does damage pipes over time. Have a plumber diagnose the cause rather than ignoring it.

Why is my water pressure low in only one bathroom?

The shut-off valve under that sink may be partially closed, or the aerator may be clogged with minerals. Check and clean both. If pressure is still low, the supply line to that bathroom may have a leak or blockage, or the valve inside the fixture may be failing. A plumber can test the line to find out which.

Does a water softener increase pressure?

No. A water softener removes minerals but does not increase pressure. However, if mineral buildup is clogging your aerators and showerheads, a softener prevents future buildup. It does not fix existing low pressure.

What is normal water pressure?

Most homes run between 50 and 80 pounds per square inch. Anything below 40 psi feels noticeably weak. You can buy a pressure gauge at any hardware store for $10 to $15 and test your own pressure by screwing it onto an outdoor faucet.

Can I increase pressure by closing my main shut-off valve partway?

No. Closing the valve reduces pressure; opening it fully is the correct position. If you need to reduce pressure because it is too high (above 80 psi), adjust the pressure regulator instead, not the main valve.