Low Water Pressure? 8 Causes and How to Fix Each One

1. Check whether the problem is in one fixture or the whole house

Before you touch anything, find out how widespread the problem is. Turn on faucets in the kitchen, bathroom and laundry room, and flush a toilet. If only one faucet is weak, the problem is in that fixture. If every fixture is weak, the problem is in your main water line, pressure regulator or municipal supply.

This one test saves a lot of wasted effort. A single weak faucet usually means a clogged aerator or cartridge, while whole-house pressure loss points to a valve, regulator or supply issue.

2. Clean or replace clogged faucet aerators

The aerator is the small mesh screen at the tip of the faucet. Mineral deposits and sediment build up in it over time and choke the flow. This is the number one cause of a single weak faucet.

Unscrew the aerator by hand or with pliers wrapped in a cloth. Rinse out the debris, soak the parts in white vinegar for 30 minutes to dissolve mineral buildup, then screw it back on. If the screen is damaged, a replacement costs just a few dollars at any hardware store.

3. Clean the showerhead

A weak shower is almost always a clogged showerhead. Hard water leaves calcium deposits in the tiny spray holes until the flow drops to a trickle.

Unscrew the showerhead and soak it in white vinegar for several hours or overnight, then scrub the holes with an old toothbrush and rinse. For a quick fix without removing it, fill a plastic bag with vinegar, tie it over the showerhead so the head is submerged, and leave it for a few hours.

4. Make sure the main shutoff valve is fully open

Your main water shutoff valve controls all water entering the house. If it was recently closed for a repair and not reopened all the way, every fixture in the house will have low pressure.

Find the valve where the water line enters your home, usually in the basement, crawl space or near the water meter. Turn a gate-style valve (round handle) counterclockwise until it stops. Turn a ball-style valve (lever handle) so the lever lines up with the pipe. Both types should be fully open.

5. Check the water meter valve outside

There is a second shutoff valve at the water meter, usually in a box near the street or sidewalk. After municipal work in your area, this valve is sometimes left partially closed.

Lift the cover and check that the valve is fully open. If you are not comfortable touching the meter box, call your water utility and ask them to check it. They will usually do this for free.

6. Test and adjust the pressure regulator

Many homes have a pressure reducing valve, a bell-shaped device on the main line where it enters the house. It keeps municipal water pressure at a safe level for your pipes, usually between 40 and 60 psi. When it wears out, usually after 10 to 15 years, it can stick and starve the whole house of pressure.

You can check your pressure with a ten-dollar gauge that screws onto an outdoor spigot. Normal residential pressure is 40 to 60 psi. If yours reads below 40 and the valves are all open, the regulator is the likely culprit. Adjusting or replacing a regulator is best left to a plumber because it involves the main line.

1. Buy a water pressure gauge at a hardware store.
2. Screw it onto an outdoor hose spigot and turn the water on fully.
3. Read the gauge: 40 to 60 psi is normal, below 40 is low.
4. Test at different times of day, since municipal pressure can dip during peak hours.

7. Look for hidden leaks

A leak in a supply line diverts water before it reaches your fixtures, which drops pressure throughout the house. Signs include an unusually high water bill, damp spots on walls or floors, the sound of running water when nothing is on, or a water meter that keeps spinning with all fixtures off.

To test for a leak, turn off every faucet and water-using appliance, then watch your water meter for 30 minutes. If the dial moves, water is escaping somewhere and you need a plumber to find it.

8. Consider corroded or clogged pipes

In older homes with galvanized steel pipes, corrosion builds up inside the pipe walls over decades until the opening shrinks to a fraction of its original size. This causes gradual pressure loss that gets worse over the years and affects the whole house.

There is no DIY fix for corroded pipes. A plumber can confirm it with a camera inspection, and the real solution is repiping the affected lines with copper or PEX. If your home is more than 40 years old and still has galvanized plumbing, this is a strong suspect.

When to call a plumber

Call a plumber if the pressure is low throughout the whole house and the valves are all open, if your pressure gauge reads below 40 psi, if you suspect a hidden leak, or if your home has old galvanized pipes. A professional can test the regulator, locate leaks with specialized equipment and tell you whether a repair or a repipe makes more sense.