Where low water pressure usually comes from

Low water pressure at one fixture or throughout your whole house usually traces back to one of a few common causes. The most frequent culprit is a clogged aerator—the small screen at the tip of your faucet that mixes air into the water stream. Mineral buildup, rust, or debris gets trapped there and restricts flow. This happens fastest in areas with hard water.

If pressure is low everywhere in your house, the problem is usually further back in your system: a partially closed shut-off valve, sediment in your water heater, or a leak somewhere in your supply lines. Occasionally your water company is the source—they may be doing work on the main, or your meter may be failing. A quick call to your water provider tells you whether the problem is on their side or yours.

Key Takeaways

  • Clean or replace the aerator (the screen at your faucet tip) first—this fixes low pressure at a single sink or shower in minutes.
  • Check that the shut-off valve under your sink or at the water meter is fully open; a partially closed valve cuts pressure throughout your house.
  • Sediment buildup in your water heater tank reduces pressure on the hot water side; flushing the tank can restore it.
  • If pressure is low everywhere and valves are open, contact your water company to confirm the problem is not on the main line.
  • Leaks in supply lines, failed pressure regulators, and corroded pipes require a licensed plumber to diagnose and repair.

Cleaning or replacing the aerator

Start here if pressure is low at only one faucet. Unscrew the aerator by hand or with a wrench (turn counterclockwise). It is usually a small cylindrical piece at the very tip of the spout. Rinse it under running water and use an old toothbrush to scrub away mineral deposits or debris. If it is heavily clogged, soak it in white vinegar for 30 minutes, then brush again.

Screw it back on and test the pressure. If it is still low after cleaning, the aerator may be damaged inside. Replacement aerators cost $3 to $8 and fit any standard faucet—take the old one to a hardware store to match the thread size, or measure the diameter. This single fix solves low pressure at kitchen sinks and bathroom faucets more often than any other step.

Opening a partially closed shut-off valve

If pressure is low at multiple fixtures or everywhere in your house, check the shut-off valves. Look under the sink where the supply lines connect—you will see one or two valves with handles. Turn the handle so it points in line with the pipe (parallel to the direction water flows). If it is perpendicular to the pipe, it is closed or partially closed.

Also check the main shut-off valve where the water line enters your house, usually near the water meter in a basement, crawlspace, or outside. It should be fully open as well. Turn it counterclockwise until it stops—do not force it. If the valve is stuck or will not turn, or if opening it does not restore pressure, stop and call a plumber. A stuck valve can break, and a valve that will not open may indicate a bigger problem downstream.

Flushing sediment from your water heater

If hot water pressure is low but cold water pressure is normal, sediment has likely accumulated inside your water heater tank. Over time, minerals settle at the bottom and block the outlet. Flushing the tank removes this buildup and usually restores pressure.

Turn off the power to your water heater (switch off the breaker for electric, or set the gas valve to pilot 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 slowly—water will be hot—and let the tank empty. Close the valve, turn the power back on, and refill the tank. Pressure should improve within an hour as the tank reheats. If you are not comfortable doing this, a plumber can do it in under an hour.

Checking for leaks in your supply lines

A leak in the pipes between your meter and your fixtures reduces pressure throughout the house. Look for wet spots on basement walls or ceilings, water stains, or soft patches in drywall. Check under sinks and around the water heater for drips or pooling water. If you find a leak, you will need a plumber to locate and repair it—leaks in buried or in-wall pipes require specialized equipment to find.

If you suspect a leak but cannot see one, turn off all water-using appliances and fixtures, then check whether your water meter is still running. A spinning meter with nothing on means water is leaking somewhere. Write down the meter reading, wait two hours without using water, and check again. If the reading has changed, you have a leak that needs professional repair.

When to call a plumber

Call a plumber if pressure remains low after you have cleaned the aerator, opened the shut-off valves, and flushed the water heater (if the problem is on the hot side). Also call if you find signs of a leak, if a valve is stuck or broken, or if pressure dropped suddenly without an obvious cause.

A plumber can test your water pressure with a gauge, check for failing pressure regulators, inspect for corroded pipes, and identify leaks you cannot see. Pressure regulators are devices that sit where the main line enters your house and keep pressure from spiking; if one fails, pressure can drop or fluctuate. Corroded galvanized steel pipes, common in older homes, narrow over time and restrict flow. Both require professional diagnosis and repair.

Confirming the problem is not on the water company's side

Before assuming the problem is in your house, call your water provider and ask whether they are doing maintenance on the main line in your area or whether they have noticed pressure issues in your neighborhood. Some water companies have a recorded message or online status page listing current work. If your meter is old, the company may also test it for free to confirm it is working correctly.

If the water company confirms the problem is on your property, you now know the issue is somewhere between your meter and your fixtures. If they report no problems and your neighbors have normal pressure, the problem is definitely in your house—start with the aerator and shut-off valves before calling a plumber.

Frequently Asked Questions

Why is my water pressure low only in the morning?

Pressure often drops in the morning when many people in your neighborhood are using water at the same time. The municipal system cannot keep up with peak demand. If pressure returns to normal later in the day, this is normal and not a problem with your house. If it stays low all day, follow the steps above to check your aerator and valves.

Can low water pressure damage my appliances?

Very low pressure can prevent dishwashers and washing machines from filling properly, leaving dishes or clothes dirty. It does not usually damage the appliances themselves, but it can make them work harder and less efficiently. Restoring normal pressure solves the problem.

What is normal water pressure?

Household water pressure is usually between 40 and 80 pounds per square inch (psi). Anything below 40 psi feels noticeably weak. A plumber can measure your pressure with a gauge for $50 to $100 if you want to know the exact number.

Does low water pressure mean I have a leak?

Not always. A clogged aerator, closed valve, or sediment in your water heater causes low pressure without any leak. Check those first. A leak is more likely if pressure dropped suddenly, if you see wet spots, or if your water meter keeps running when nothing is on.

Should I use a water pressure booster pump?

A booster pump can raise pressure if your home is at high elevation or far from the water main, but it is expensive ($1,500 to $3,000 installed) and should be a last resort. Fix the aerator, valves, and sediment first—these solve most low-pressure problems at no cost or very low cost.