Check Your Main Water Valve and Pressure Regulator First

Low water pressure usually comes from one of three places: a partially closed valve, a faulty pressure regulator, or a problem inside your home's pipes. Before you call a plumber, check whether someone has turned down your main water shutoff valve — the large valve where the water line enters your house from the street. It should be fully open (the handle points along the pipe, not across it). If it is partially closed, turn it counterclockwise until it stops.

Next, locate your pressure regulator, a bell-shaped brass fitting usually mounted on the main water line near the shutoff valve. If your home has one, it controls how much pressure enters your house. A regulator that has failed or been set too low will reduce pressure throughout the house. You can test the pressure with a pressure gauge (available at hardware stores for $10 to $20) by screwing it onto an outdoor faucet. Normal household pressure is 40 to 60 pounds per square inch (psi). If your gauge reads below 40 psi and your main valve is fully open, the regulator may need adjustment or replacement.

Key Takeaways

  • Check that your main water shutoff valve is fully open and that no one has accidentally closed it partway.
  • A pressure regulator set too low or failing will reduce pressure throughout your entire house, and you can test this with a $10 to $20 pressure gauge.
  • Mineral buildup inside aerators and showerheads is the most common cause of low pressure in a single fixture, and cleaning them takes 15 minutes.
  • If pressure is low only in one room or on one floor, a closed isolation valve or a leak in that section of pipe is usually responsible.
  • Water company pressure problems affect your whole house and require a call to your utility; low pressure from a regulator or valve requires a plumber.

Clean Aerators and Showerheads to Restore Single-Fixture Pressure

If pressure is low at only one faucet or showerhead, mineral deposits clogging the aerator are almost always the cause. An aerator is the small screen at the tip of a faucet that mixes air into the water stream. Over time, calcium and other minerals build up inside it and block flow. Unscrew the aerator by hand (turn counterclockwise) or use a wrench if it is stuck. Soak it in white vinegar for 30 minutes to dissolve the mineral deposits, then scrub the screen with an old toothbrush and rinse it thoroughly before screwing it back on.

Showerheads work the same way. Unscrew yours and soak it in a plastic bag filled with white vinegar — you can hang the bag around the showerhead with a rubber band so the head stays submerged. After 30 minutes, brush out the holes with a toothbrush and rinse. If the holes are still blocked, use a thin wire or a straightened paperclip to poke through each one. This fix costs nothing and solves low pressure at a single fixture in most cases.

Look for Closed Isolation Valves in That Section of Pipe

If pressure is low in one room or on one floor but normal everywhere else, an isolation valve — a small shutoff valve installed under sinks, behind toilets, or along supply lines — may be partially closed. These valves let you shut off water to one fixture without affecting the rest of the house. Check under every sink and behind every toilet in the low-pressure area. The valve handle should point along the pipe (open) rather than across it (closed). If you find one that is partially closed, turn it counterclockwise until it stops.

If all isolation valves are fully open and pressure is still low in one area, a leak or blockage in the pipes serving that section is likely. This requires a plumber to locate and repair, but knowing which room or floor has the problem will help them narrow down where to look.

Adjust or Replace a Faulty Pressure Regulator

If your pressure gauge reads below 40 psi and your main valve is fully open, your pressure regulator may be set too low or may have failed. Some regulators have an adjustment screw on top that you can turn with a wrench. Turning it clockwise increases pressure; counterclockwise decreases it. Adjust it slowly — one quarter turn at a time — and retest with your pressure gauge after each adjustment. Stop when you reach 50 to 55 psi. Do not exceed 60 psi, as high pressure damages pipes and fixtures over time.

If the regulator has no adjustment screw, or if adjusting it does not raise pressure, the regulator has likely failed internally and needs replacement. A new regulator costs $50 to $150 plus installation. If you are comfortable with basic plumbing, you can replace it yourself by turning off the main valve, unscrewing the old regulator, and screwing on a new one of the same size. If you are not, a plumber can do it in under an hour.

Identify Leaks or Blockages in Your Home's Pipes

If pressure is low throughout your house and your main valve and regulator are working correctly, a leak or mineral blockage inside your home's pipes may be the cause. A slow leak will not always be obvious — check your water meter while no water is running. If the meter is moving, you have a leak somewhere. Leaks in buried or in-wall pipes are expensive to find and repair, so call a plumber who can use pressure testing or acoustic equipment to locate them.

Mineral buildup inside old galvanized steel pipes is another possibility, especially in homes built before 1980. As minerals accumulate over decades, they narrow the pipe opening and reduce flow. This affects the whole house gradually and cannot be fixed without replacing the pipes. A plumber can confirm this by testing pressure at different points in your system.

Contact Your Water Company if Pressure Drops Suddenly

If pressure was normal yesterday and dropped suddenly throughout your entire house, the problem may be on the water company's side. Main breaks, hydrant work, or pressure adjustments in your neighborhood can affect multiple homes at once. Call your water utility and report the low pressure. They can tell you whether work is happening in your area and when pressure should return to normal. They may also send someone to check the meter and the line leading to your house at no charge.

While you wait for the utility to respond, you can still use your water normally — low pressure is inconvenient but not dangerous. If pressure does not return within a few hours, or if the utility finds no problem on their end, then the issue is in your home and you should have a plumber inspect your main valve, regulator, and pipes.

When to Call a Plumber

You can handle a closed valve, a clogged aerator, or a regulator adjustment yourself. Call a plumber if pressure remains low after you have checked the main valve, cleaned aerators, and adjusted the regulator. Also call if pressure is low in only one section of your home and isolation valves are open — this usually means a leak or blockage that requires professional tools to locate. A plumber's visit typically costs $100 to $200 for diagnosis and a straightforward fix like regulator replacement; finding and repairing a hidden leak will cost more.

If your water company has ruled out problems on their end and your home's pressure regulator is working, the issue is almost certainly inside your pipes. A plumber can pressure-test your system to find leaks and blockages that you cannot see.

Frequently Asked Questions

Is low water pressure a sign of a serious problem?

Not always. A clogged aerator or a closed valve causes low pressure but is harmless and straightforward to fix. A slow leak or mineral buildup is more serious and will get worse over time, but it is not an emergency. A sudden pressure drop across your whole house may mean a main break, which the water company will address.

Can I raise water pressure above 60 psi?

You can, but you should not. Pressure above 60 psi puts stress on pipes, joints, and fixtures and shortens their lifespan. It also wastes water and can cause leaks. Keep your regulator set between 50 and 60 psi for the best balance of flow and durability.

What does a pressure regulator cost to replace?

A new regulator costs $50 to $150 depending on the brand and size. If you install it yourself, that is your only cost. If a plumber installs it, add $100 to $200 for labor, bringing the total to $150 to $350.

Why is pressure low only in my shower but normal at the kitchen sink?

The showerhead aerator is almost certainly clogged with mineral deposits. Unscrew it, soak it in vinegar for 30 minutes, brush out the holes, and screw it back on. This fixes the problem in most cases.

How do I know if I have a water leak inside my walls?

Check your water meter while no water is running in the house. If the meter moves, you have a leak. You may also notice soft spots in walls, discolored drywall, or a musty smell. A plumber can use acoustic listening equipment or pressure testing to pinpoint where the leak is.