Start with the pressure regulator and main shutoff valve
Low water pressure often starts at your meter or where the main line enters your house. Most homes have a pressure regulator — a bell-shaped brass fitting on the incoming water line — that deliberately reduces pressure to protect your pipes. If the regulator is set too low, you feel weak flow everywhere in the house.
Check the regulator's adjustment screw on top. It usually has a locknut below it. Turn the screw clockwise a quarter turn, then test your pressure at a sink. If pressure improves, you have found the problem. If the regulator is stuck or will not adjust, it may need replacement — a plumber can do this in under an hour.
While you are there, check that the main shutoff valve (the handle near your meter) is fully open. A partially closed valve cuts pressure throughout the house. The handle should point along the pipe direction, not across it.
Key Takeaways
- The pressure regulator at your meter controls flow to the whole house and can be adjusted with a wrench if pressure is too low.
- Mineral buildup inside aerators and showerheads is the most common cause of weak pressure in one room or fixture.
- A clogged main water line or corroded galvanized pipes inside the house require a plumber to diagnose and fix.
- If only one fixture has low pressure, start by cleaning or replacing the aerator before calling for service.
Clean aerators and showerheads to restore flow
Mineral deposits clog the tiny screens in faucet aerators and showerheads. This is the easiest fix and costs nothing. Unscrew the aerator from the end of the faucet (turn counterclockwise by hand or with a wrench if it is stuck). Soak it in white vinegar for two hours, then scrub the screen with an old toothbrush and rinse.
For showerheads, unscrew the head from the arm, soak it in vinegar the same way, and clean the holes with a toothpick or small wire. Reinstall and test. If pressure returns to normal, the problem was mineral buildup. If pressure is still weak, the clog is deeper in the line.
If the aerator is badly corroded or the holes are too small to clean, buy a replacement aerator at any hardware store for two to five dollars. They screw on the same way the old one came off.
Check for leaks that waste pressure
A leak anywhere in your water line — even a small one you cannot see — reduces pressure throughout the house. Start by turning off all water use, then look at your water meter. If the numbers are still moving, water is leaking somewhere.
Check under sinks, in the basement, and around the water heater for wet spots or dripping. Look at the walls for soft spots or discoloration. If you find a leak, you will need a plumber to locate and repair it. If you cannot find a visible leak but the meter is running, the leak is likely inside a wall or under the foundation, which requires professional detection equipment.
Flush the main water line if pressure is low everywhere
Sediment and mineral buildup inside the main water line can choke flow to the whole house. To flush the line, turn off the main shutoff valve, then open the lowest faucet in your house (usually a basement sink or outdoor spigot) and let water drain until it stops. Close that faucet, turn the main valve back on, and run water at the lowest faucet again for several minutes until the water runs clear.
This removes loose sediment that has collected in the line. If pressure improves, you are done. If pressure is still low after flushing, the buildup is likely inside the pipes themselves, which a plumber can address by installing a whole-house water filter or, in severe cases, replacing corroded galvanized pipe.
Identify whether the problem is inside or outside your house
Turn on a cold-water faucet and let it run for 30 seconds. If pressure is weak, the problem is likely on the water company's side of the meter or in the main line from the street. Call your water company to report low pressure — they will check for problems on their side at no cost to you.
If cold water pressure is normal but hot water is weak, the problem is your water heater or the hot-water line. Check the shutoff valve on the hot-water inlet (the cold line feeding the heater) to make sure it is fully open. If it is open and pressure is still low, sediment inside the heater is blocking flow, and the heater may need flushing or replacement.
If pressure is weak in only one room or one fixture, the problem is local to that line or fixture, not the whole house. Start with cleaning the aerator, then check for a closed shutoff valve under that sink.
Replace old galvanized pipe if pressure is chronically low
Homes built before the 1980s often have galvanized steel pipe for water lines. Over decades, rust and mineral deposits build up inside the pipe, narrowing the opening and strangling flow. If your house is old, pressure has always been weak, and flushing did not help, galvanized pipe is the likely culprit.
Replacing galvanized pipe is a job for a licensed plumber. They will run new copper or PEX plastic pipe alongside or through the walls to replace the old line. The cost depends on how much pipe needs replacement — a single line might cost $500 to $1500, while replacing all water lines in a house costs several thousand dollars. Get quotes from two or three plumbers before deciding.
If cost is a barrier, you can start by replacing just the main line from the meter to the house, which improves pressure more than replacing individual branch lines.
Install a water pressure booster pump for persistent low pressure
If your water company delivers low pressure to your meter (common in rural areas or at the top of a hill), or if you have already fixed the obvious problems and pressure is still weak, a booster pump can help. These pumps sit on the main water line after the meter and push water through your house at higher pressure.
A booster pump costs $300 to $800 installed, depending on the model and your plumber's labor rate. The pump runs on electricity and turns on automatically when you open a faucet. It is a permanent solution but more expensive than fixing a regulator or cleaning an aerator, so try the simpler fixes first.
Some booster pumps include a pressure tank that stores water under pressure, which also helps with pressure spikes when multiple fixtures run at once. Ask your plumber whether a tank is worth the extra cost for your situation.
Frequently Asked Questions
Can I adjust the pressure regulator myself?
Yes. Locate the regulator on the main water line (usually near the meter), find the adjustment screw on top, and turn it clockwise a quarter turn with a wrench. Test pressure at a sink. If it improves, turn it another quarter turn. Stop when pressure feels normal. If the regulator will not budge or leaks after adjustment, a plumber should replace it.
Why is pressure weak in only one bathroom?
Check the shutoff valve under that sink — it may be partially closed. If the valve is fully open, clean the aerator on the faucet and the showerhead. If pressure is still weak after cleaning, the hot-water line to that bathroom may have mineral buildup, which requires a plumber to flush or replace.
How do I know if my water company is causing low pressure?
Call your water company and report the problem. They will check pressure at your meter and on the street. If street pressure is normal but your meter shows low pressure, the problem is your main line or regulator. If street pressure is already low, the company may be able to increase it or explain why it cannot.
Is a booster pump worth the cost?
Only if simpler fixes have not worked. Try adjusting the regulator, cleaning aerators, and flushing the main line first. If pressure is still weak and your water company confirms they deliver low pressure to your area, a booster pump is a permanent solution that costs $300 to $800 installed.
What should water pressure be in a home?
Normal household water pressure is 40 to 60 pounds per square inch (PSI). Below 40 PSI, showers feel weak and washing machines fill slowly. Above 80 PSI, you risk damage to pipes and fixtures. If you want to measure your pressure, buy a pressure gauge at a hardware store for $10 to $15 and screw it onto an outdoor spigot.