What causes low water pressure and how to fix it

Low water pressure usually comes from one of three places: a problem inside your home's plumbing, an issue with your water meter or main line, or a problem at your water supplier's end. You can often fix the first type yourself. The second and third types require a plumber or your water company.

Start by checking whether the problem is everywhere in your home or just one fixture. Turn on the kitchen sink, then a bathroom sink, then a shower. If pressure is low everywhere, the issue is likely your main water line, pressure regulator, or water meter. If it's low in only one or two places, the problem is usually a clogged aerator, a closed valve, or mineral buildup in that specific line.

Key Takeaways

  • Low pressure everywhere in your home usually points to your pressure regulator, main shutoff valve, or water meter — all things a plumber needs to check.
  • Low pressure in one fixture is often a clogged aerator (the screen at the faucet tip), which you can clean yourself in minutes.
  • Mineral buildup inside pipes and fixtures is common in hard water areas and can be dissolved with vinegar or replaced by a plumber.
  • Your water supplier can tell you the pressure at the street; if it's below 40 PSI, the problem is not in your home.

Clean or replace the aerator on the affected faucet

The aerator is a small screen screwed onto the tip of your faucet. It mixes air into the water stream and catches sediment and mineral deposits. Over time it clogs, and pressure drops at that one fixture.

Unscrew the aerator by hand (turn counterclockwise). If it's stuck, wrap the base in a cloth and use pliers — grip the cloth, not the aerator itself, to avoid scratching the finish. Rinse the aerator under hot water and use an old toothbrush to scrub away any white or brown buildup. If the screen is torn or the aerator is badly corroded, replace it with a new one from any hardware store (they cost a few dollars and come in standard sizes).

Screw the aerator back on and test the pressure. If it's still low, the problem is deeper in that line — mineral buildup inside the faucet body or the supply line itself.

Check that all shutoff valves are fully open

Your home has a main water shutoff valve where the water line enters from the street. You may also have individual shutoff valves under sinks and behind toilets. Any of these can be partially closed, which reduces pressure.

Locate your main shutoff valve (usually in the basement, crawl space, or outside near the foundation). The valve handle should point in the same direction as the pipe — that means it's open. If the handle is perpendicular to the pipe, it's closed or partially closed. Turn it to align with the pipe.

Check the shutoff valves under your kitchen and bathroom sinks as well. They should be fully open (turn counterclockwise until they stop). If you find one that was closed or partially closed, open it fully and test your pressure again.

Flush sediment from your water heater

If pressure is low only in your hot water lines, sediment has likely built up inside your water heater tank. Cold water pressure is normal, but hot water pressure is weak.

Turn off the power to your water heater (switch the breaker for electric, or turn the gas knob to "off" for gas). Attach a garden hose to the drain valve at the bottom of the tank and run it to a floor drain or outside. Open the drain valve and let water run for 30 seconds to a minute. You may see brown or cloudy water — that's sediment leaving the tank. Close the drain valve, turn the power back on, and test your hot water pressure.

If sediment buildup is severe, you may need to drain the entire tank, which takes longer and is easier with a plumber's help. But a quick flush often restores enough pressure to notice the difference.

Have a plumber check your pressure regulator

Most homes have a pressure regulator — a bell-shaped device on the main water line just after the shutoff valve. It keeps water pressure from getting too high and damaging your pipes and fixtures. If it fails or gets stuck, pressure drops everywhere in the home.

A plumber can test the regulator with a pressure gauge (a straightforward tool that screws onto an outdoor faucet). Normal household water pressure is between 40 and 80 PSI. If the gauge reads below 40 PSI and your water company confirms pressure at the street is normal, the regulator is likely the problem and needs replacement.

Replacing a pressure regulator is not a DIY job — it requires turning off the main water line and working with the pressurized system. Call a licensed plumber for this one.

Contact your water supplier if pressure is low at the meter

If a plumber has ruled out problems inside your home, the issue is either your water meter or the main line from the street. Your water company owns and maintains both.

Call your water supplier and ask them to check the pressure at the meter. They can do this in minutes. If pressure at the meter is below 40 PSI, the problem is on their side — either the main line is partially blocked or pressure in your neighborhood is low. If pressure at the meter is normal but low inside your home, you have a clog or leak in the line between the meter and your house, and you'll need a plumber to locate and repair it.

Some water companies offer free pressure checks; others charge a small fee. It's worth asking before they send someone out.

Deal with mineral buildup in hard water areas

In areas with hard water, minerals like calcium and magnesium build up inside pipes and fixtures over time. This narrows the pipe opening and reduces pressure gradually — you may not notice it until pressure is noticeably low.

For a single faucet, soak the aerator in white vinegar for 30 minutes to dissolve mineral deposits, then scrub with an old toothbrush. For a showerhead, unscrew it and soak it in a plastic bag filled with vinegar overnight, then scrub and rinse.

If mineral buildup is severe throughout your home, a whole-house water softener can prevent future deposits, but it's an investment. A plumber can assess whether your water hardness is high enough to justify one. In the meantime, a plumber can also flush your main line or replace sections of pipe that are heavily clogged.

Frequently Asked Questions

Is low water pressure a sign of a leak?

Not always. A leak usually causes low pressure in one area or one line, and you'll see water damage or wet spots. Low pressure everywhere is more likely a regulator, valve, or meter issue. If you suspect a leak, a plumber can pressurize your system and listen for the sound of escaping water, or use a leak detection tool.

Can I increase water pressure above 80 PSI?

Your pressure regulator is designed to keep pressure below 80 PSI to protect your pipes and fixtures. Pressure above 80 PSI can damage water heaters, washing machines, and dishwashers. If you want higher pressure, a plumber can adjust the regulator, but only within safe limits — usually no higher than 75 PSI.

Why is my water pressure low only in the morning?

This often happens when sediment settles in your pipes overnight. Run a cold water tap for a minute or two to flush the sediment out. If it happens every morning, your water heater may need flushing, or sediment in the main line may need professional cleaning.

How much does it cost to fix low water pressure?

Cleaning an aerator is free. Replacing a pressure regulator typically costs $300 to $500 including labor. A plumber's diagnostic visit to check your system usually costs $100 to $200. Call a few local plumbers for estimates before deciding.