Start by finding where the pressure drop happens

Low water pressure usually comes from one of three places: the supply line from the street, the main shutoff valve, or the pipes and fixtures inside your home. The fastest way to narrow it down is to check whether the problem is everywhere or just one faucet.

Turn on a faucet in your kitchen, then check a bathroom sink, a shower, and an outdoor hose if you have one. If pressure is low everywhere, the issue is likely before the main shutoff valve. If only one or two fixtures are weak, the problem is in those specific lines or the fixture itself.

You can also call your water company and ask if they are doing work in your area or if they have a record of low pressure on your street. This takes five minutes and rules out a problem you cannot fix yourself.

Key Takeaways

  • Low pressure everywhere in the house usually points to the main shutoff valve or the supply line from the street, not individual fixtures.
  • A partially closed main shutoff valve is the single most common cause and takes seconds to fix by turning the handle fully counterclockwise.
  • Mineral buildup inside aerators and showerheads can be cleared by soaking them in white vinegar for two to four hours.
  • If pressure is low in only one fixture, the problem is in that line or the fixture itself, and you can often fix it without calling a plumber.
  • Water company pressure problems and main line leaks require a call to your utility or a licensed plumber, not a DIY fix.

Check and open the main shutoff valve

The main shutoff valve controls water flow into your entire house. It is usually located near the water meter, in a basement, crawl space, or utility closet. Look for a valve with a handle shaped like a wheel or a lever.

If the handle is a wheel, turn it counterclockwise (left) until it stops. If it is a lever, it should point in the same direction as the pipe when fully open — if it is perpendicular to the pipe, it is partially or fully closed. Turn it so it lines up with the pipe.

After opening the valve, wait a few seconds and check your water pressure again. This single step fixes the problem in roughly one out of every five homes with low pressure. If pressure improves but is still weak, the valve itself may be partially stuck or damaged, and you should call a plumber to replace it.

Clean aerators and showerheads clogged with mineral buildup

Aerators are the small screens at the tip of faucets. Showerheads have tiny holes that can clog with mineral deposits, especially in areas with hard water. Both are straightforward to clean and often restore pressure when ready.

For a faucet aerator: unscrew it by hand or with a wrench, rinse it under running water, and use an old toothbrush to scrub away white or tan deposits. If buildup is heavy, soak the aerator in a bowl of white vinegar for two to four hours, then scrub again. Screw it back on and test the pressure.

For a showerhead: unscrew it from the shower arm, fill a plastic bag with white vinegar, and submerge the showerhead in the bag for two to four hours. You can rubber-band the bag to the shower arm so you do not have to hold it. After soaking, use a toothpick or small nail to poke out any remaining deposits from the holes, rinse thoroughly, and screw it back on.

If you have low pressure at only one or two fixtures and cleaning the aerator does not help, the clog is likely deeper in the line, and you may need a plumber to clear it.

Look for leaks in visible pipes

A leak in the main supply line or in pipes inside your walls can reduce pressure throughout the house. Check under sinks, in the basement, and around the water heater for wet spots, dripping water, or pooling.

If you find a leak, turn off the main shutoff valve when ready and call a licensed plumber. Do not try to patch a pressurized line yourself — the repair requires soldering or professional-grade fittings and should be done by someone trained to do it safely.

If you see no visible leaks but pressure is still low everywhere, the leak may be in the line running from the street to your house, buried underground. This also requires a plumber or your water company to locate and repair.

Check the pressure regulator if your home has one

Some homes have a pressure regulator — a bell-shaped device usually mounted on the main water line near the shutoff valve. It keeps incoming pressure from the street from being too high and damaging your pipes.

If the regulator is faulty, it can reduce pressure too much. You can test it with an inexpensive pressure gauge, which screws onto any outdoor hose bib. Normal household water pressure is between 40 and 80 pounds per square inch (PSI). If your gauge reads below 40 PSI and the main shutoff valve is fully open, the regulator may be failing.

Replacing a pressure regulator is a job for a licensed plumber. Do not attempt to adjust or disassemble it yourself.

Know when to call a plumber or your water company

Call your water company if pressure is low everywhere and you have ruled out the main shutoff valve, aerators, and visible leaks. They can check the pressure at the meter and tell you whether the problem is on their side of the line or yours. This call is free.

Call a licensed plumber if you find a leak, if the pressure regulator appears faulty, if the main shutoff valve will not open fully, or if pressure is low in one fixture and cleaning the aerator did not help. A plumber can also use specialized equipment to find leaks inside walls and diagnose problems you cannot see.

Do not wait to call if you see water pooling near the foundation or meter — a major leak can waste thousands of gallons and damage your home.

Frequently Asked Questions

Why is my water pressure low in just the shower but fine everywhere else?

The showerhead aerator is almost certainly clogged with mineral buildup. Unscrew the showerhead, soak it in white vinegar for two to four hours, and use a toothpick to clear the holes. If that does not work, the problem is in the shower valve itself, and a plumber can replace the cartridge inside.

Can I turn the main shutoff valve all the way open if it is stuck?

Do not force it. If the handle is stuck or very stiff, the valve may be corroded inside. Forcing it can break it, leaving you unable to shut off water in an emergency. Call a plumber to replace it instead.

What is normal water pressure, and how do I measure it?

Normal household pressure is 40 to 80 PSI. You can measure it with a pressure gauge that screws onto an outdoor hose bib — they cost five to fifteen dollars at any hardware store. Screw it on, turn on the hose, and read the number on the dial.

Does low water pressure mean I have a leak?

Not always. A partially closed shutoff valve, clogged aerators, or a faulty pressure regulator are more common causes. Check those first. If you find no visible leaks and the shutoff valve is fully open, the leak may be underground or inside a wall, and you will need a plumber to locate it.

Should I replace old pipes if water pressure is low?

Not automatically. Old galvanized steel pipes can corrode and reduce pressure, but replacing them is expensive and should be a last resort. Have a plumber diagnose the actual cause first — it is often something much cheaper to fix.