Start with the pressure regulator and main shutoff valve

Low water pressure usually comes from one of three places: your pressure regulator is set too low, debris is blocking the line, or a leak is stealing water before it reaches your fixtures. The fastest fix is checking your pressure regulator, a bell-shaped brass valve usually mounted on the main water line where it enters your house, often in the basement or under the kitchen sink.

The regulator has a screw on top that you can turn to raise pressure. Turn it clockwise to increase pressure, counterclockwise to decrease it. Most homes run between 40 and 60 pounds per square inch (PSI). If your regulator screw turns freely with no resistance, the internal spring may be broken and the regulator needs replacement. Before you adjust anything, buy a water pressure gauge (about $10 at any hardware store) and screw it onto an outdoor faucet to see what pressure you actually have. This tells you whether the problem is real or just feels that way.

Key Takeaways

  • Check your water pressure with a gauge on an outdoor faucet before making any changes—most homes should read between 40 and 60 PSI.
  • The pressure regulator screw (usually on the main water line in your basement) can be turned clockwise to raise pressure, but only adjust it a few turns at a time.
  • Sediment and mineral buildup in aerators and screens block flow and are the most common cause of low pressure at individual faucets.
  • If only one room has low pressure, the problem is usually in that room's supply line or fixtures, not your main line.
  • Water leaks hidden in walls or under floors steal pressure throughout the house and require a plumber to locate and repair.

Clean aerators and screens on every faucet

If pressure is low at only one or two faucets, the problem is almost always sediment trapped in the aerator—the small screen at the tip of the faucet. Unscrew the aerator by hand (turn counterclockwise) and hold it up to the light. If you see white, tan, or rust-colored buildup, that is mineral deposits or sediment blocking the holes.

Soak the aerator in white vinegar for 30 minutes to dissolve mineral deposits, then scrub it with an old toothbrush and rinse under running water. Screw it back on and test the pressure. If pressure is still low, the aerator screen may be too fine for your water quality. You can buy a replacement aerator at any hardware store for $3 to $8—bring the old one to match the thread size. For shower heads, the same method works: unscrew, soak in vinegar, scrub, and rinse.

Check for leaks in supply lines and fixtures

A hidden leak in your walls, under your floor, or behind your toilet will lower pressure throughout the house because water is escaping before it reaches your faucets. The easiest way to spot a leak is to turn off all water-using appliances (washing machine, dishwasher, ice maker) and look at your water meter. If the meter keeps moving, you have a leak.

Check under sinks and around the base of toilets for wet spots or water stains. Look at your water bill—a sudden jump in usage with no change in your habits points to a leak. If you find water pooling or staining, that leak is in a visible spot and you can call a plumber with a clear description. If the meter moves but you see no water, the leak is in a supply line inside a wall or under the floor, and a plumber will need to use a listening device to locate it. Fixing hidden leaks is not a DIY job.

Clean or replace the main water shutoff valve screen

Where your main water line enters your house, there is often a small screen inside the shutoff valve that catches sediment before it reaches your pipes. Over time, this screen clogs and restricts flow. To check it, you need to shut off the main water valve and unscrew the valve body—this is a job for someone comfortable with basic plumbing, or you can call a plumber to do it in 30 minutes.

If you decide to do it yourself, have a bucket ready because water will spill. Unscrew the large nut holding the valve body to the pipe, pull out the valve, and look for a small screen inside. If it is clogged with sediment, rinse it under running water or soak it in vinegar. If it is damaged, buy a replacement screen at a plumbing supply store (usually $5 to $15) and install it the same way. Turn the main valve back on slowly and check for leaks at the connection.

Raise the pressure regulator setting gradually

Once you know your current pressure with a gauge, you can adjust the regulator if it is set below 40 PSI. Locate the adjustment screw on top of the regulator and turn it clockwise one full turn. Wait 30 seconds, then check the pressure again with your gauge. Repeat in one-turn increments until you reach your target pressure, usually 50 to 60 PSI.

Do not jump the pressure up all at once—high pressure stresses pipes, fixtures, and appliances and can cause leaks or damage. If you turn the screw and nothing happens, or if pressure drops instead of rising, the regulator is faulty and needs replacement. A new pressure regulator costs $50 to $150 and takes a plumber 30 to 45 minutes to install. If your house has no regulator at all (older homes sometimes do not), you may want one installed to protect your plumbing from pressure spikes when the municipal water main pressure changes.

Know when to call a plumber

Call a plumber if pressure is low throughout the house and adjusting the regulator does not help, or if you find signs of a leak you cannot locate. Also call if the regulator screw does not turn or turns without resistance—both mean the regulator needs replacement. If pressure is fine at the street but low inside your house, the problem is in your home's supply line, and a plumber can pressure-test the line to find where it is leaking or blocked.

A plumber visit usually costs $100 to $200 for diagnosis and a straightforward fix like cleaning a valve screen or replacing a regulator. If a hidden leak is found, repair costs depend on where the leak is and how much of the wall or floor needs to be opened. Getting a diagnosis first helps you understand what you are paying for.

Frequently Asked Questions

How high should I set my water pressure?

Most homes run best between 50 and 60 PSI. Below 40 PSI and showers feel weak; above 80 PSI and you risk damage to pipes, water heaters, and washing machines. Check your pressure gauge while someone is running a faucet—pressure should stay steady, not drop suddenly when another faucet opens.

Will low water pressure damage my appliances?

Low pressure does not damage appliances, but it makes them work poorly. Dishwashers and washing machines need at least 20 PSI to function. High pressure (above 80 PSI) is what damages appliances by stressing seals and connections over time.

Can I increase pressure if my water comes from a well?

Well systems use a pressure tank and pump instead of a regulator. If pressure is low, the pump may be failing or the tank may have lost air pressure. This requires a well technician to diagnose—it is not a DIY fix.

Why is pressure low in only one room?

A single room with low pressure usually has a clogged aerator, a partially closed shutoff valve under that sink or in that wall, or a leak in that room's supply line. Check the aerator first, then look for a shutoff valve you may have accidentally closed.

Should I turn off the water before adjusting the pressure regulator?

No, the regulator works while water is flowing. You do need to turn off the main valve if you are opening the valve body to clean the screen inside, but not for adjusting the screw on top.