Where low water pressure comes from, and what you can fix yourself
Low water pressure usually comes from one of three places: a problem at the meter or main line (which the water company handles), a clogged or partially closed valve in your home (which you can fix), or sediment buildup in aerators and showerheads (which takes 20 minutes). Start by checking whether the problem is everywhere in the house or just one fixture. If it's one sink or shower, the aerator is almost certainly clogged. If it's the whole house, look for a shut-off valve that's been left partially closed, or call your water company to check the meter.
Before you spend money on a pressure booster pump or call a plumber, try the three fixes below. They cost nothing or very little, and they solve the problem in most homes.
Key Takeaways
- Low pressure in one fixture usually means the aerator (the screen at the faucet tip) is clogged with sediment and can be cleaned in minutes by unscrewing it and rinsing it under running water.
- Low pressure throughout the whole house often means the main shut-off valve under the sink or near the meter has been left partially closed and needs to be turned fully open.
- If you have an older home with galvanized steel pipes, corrosion inside the pipes can reduce pressure over time and may require replacing those pipes.
- A pressure regulator that has failed can lower pressure to the whole house and costs $150 to $300 to replace, but this is less common than a clogged aerator or closed valve.
- If pressure is low only when you run hot water, the problem is in your water heater, not your main line.
Clean the aerator on a single faucet or showerhead
An aerator is the small screen at the tip of a faucet or the insert inside a showerhead. It mixes air into the water stream and catches sediment. Over time, mineral deposits and rust particles clog it, and pressure drops to that fixture alone.
To clean it: unscrew the aerator by hand (or use a wrench if it's stuck). Rinse it under hot running water and use an old toothbrush to scrub away any white or brown buildup. If the screen is badly corroded, soak it in white vinegar for an hour, then scrub again. Screw it back on and test the pressure. If pressure is still low, the aerator may be too damaged to clean—buy a replacement for $3 to $8 at any hardware store and screw it on.
For a showerhead, the process is the same: unscrew it from the shower arm, clean or replace the internal aerator, and screw it back on. If you cannot unscrew the showerhead by hand, wrap a cloth around it and use a wrench to avoid scratching the finish.
Check that the main shut-off valve is fully open
Every home has a main shut-off valve where the water line enters the house. It is usually under the kitchen sink, in the basement, or outside near the meter. If someone has left it partially closed, pressure will be low everywhere.
Locate the valve and look at the handle. If it is a ball valve (a lever handle), it should point in the same direction as the pipe—parallel to it means fully open, perpendicular means fully closed. If it is a gate valve (a round knob), turn it counterclockwise until it stops. Do not force it. If the valve is stuck or will not turn, do not break it—call a plumber.
After opening the valve fully, run water at a sink for 30 seconds to flush any air from the line, then check pressure at other fixtures. If pressure improves, the problem was the valve. If it does not improve, move to the next step.
Look for a pressure regulator and check its setting
Many homes have a pressure regulator—a bell-shaped device on the main water line, usually near the meter or main shut-off valve. It keeps pressure from getting too high and damaging pipes and appliances. If the regulator has failed or been set too low, pressure drops throughout the house.
A working regulator should show pressure between 40 and 80 pounds per square inch (psi). If you have a pressure gauge (or can borrow one from a neighbor), screw it onto an outdoor faucet or a hose bib and turn the water on. If the reading is below 40 psi, the regulator may need adjustment or replacement. Adjusting it requires turning a screw on top of the regulator, but this is a job for a plumber unless you are comfortable working with water pressure equipment. Replacement costs $150 to $300.
If you do not have a pressure gauge, you can rent one from a tool rental shop for $5 to $10 per day, or ask a plumber to test pressure for you (usually $75 to $150 for a service call).
Flush sediment from the water heater if pressure is low only for hot water
If cold water pressure is normal but hot water pressure is weak, the problem is inside your water heater, not your main line. Sediment builds up at the bottom of the tank and can clog the outlet pipe.
To flush the heater: turn off the power (for electric) or gas (for gas), turn off the cold water inlet valve at the top of the tank, and attach a garden hose to the drain valve at the bottom. Run the hose to a floor drain or outside, open the drain valve, and let water run until it runs clear. This usually takes 10 to 20 minutes. Close the drain valve, turn the inlet valve back on, and turn power or gas back on. Wait 10 minutes before running hot water.
If flushing does not improve pressure, the outlet pipe inside the heater may be clogged, and the heater may need to be replaced. This is a job for a plumber.
When to call a plumber instead of trying to fix it yourself
Call a plumber if the shut-off valve will not turn, if the pressure regulator needs adjustment or replacement, or if you are not comfortable working with water lines. Also call if low pressure started suddenly after a repair or construction work nearby—the water company may have flushed the line and left sediment in your pipes, and a plumber can flush your home's lines to clear it.
If your home was built before 1980 and has low pressure throughout the house, the pipes themselves may be corroded. Galvanized steel pipes corrode from the inside over decades, narrowing the passage for water. Replacing them is expensive ($3,000 to $8,000 depending on the size of the house), but it is the only permanent fix. A plumber can tell you whether this is the problem by testing pressure at the meter versus pressure inside the house.
Pressure booster pumps: when they make sense and when they do not
A pressure booster pump is an electric pump that increases water pressure throughout the house. They cost $300 to $800 installed and use electricity to run. They are useful if your water company delivers low pressure (below 40 psi) and you have already ruled out problems in your own home. They are not useful if the problem is a clogged aerator, a closed valve, or a failed regulator—fix those first.
Before buying a booster pump, have a plumber test pressure at the meter to confirm that the water company is delivering low pressure, not your home's pipes. If the meter shows normal pressure (50 to 80 psi) but your fixtures show low pressure, the problem is inside your home and a booster pump will not help.
Frequently Asked Questions
Why is my water pressure low only in the morning?
Low pressure in the morning often means air is trapped in the lines overnight. Run water at a sink for two to three minutes until the stream becomes steady and clear. If pressure stays low after that, the problem is not air. Check whether the pressure regulator is set correctly or whether a valve was partially closed.
Can I increase water pressure by adjusting the pressure regulator myself?
The regulator has a screw on top that can be turned to raise or lower pressure, but adjusting it without a pressure gauge can damage your pipes or appliances if you set it too high. Have a plumber test and adjust it, or rent a pressure gauge and follow the regulator's manual. Most regulators should be set between 50 and 60 psi.
What if I cleaned the aerator but pressure is still low in that one fixture?
The problem may be inside the faucet or showerhead itself. Try soaking the entire fixture in vinegar for an hour to dissolve mineral buildup. If that does not work, the internal valve may be worn and the fixture may need to be replaced. A new faucet costs $50 to $200 depending on quality.
Does low water pressure mean I have a leak?
Not always. A leak would usually show up as wet spots in the yard, basement, or walls, or as a higher water bill. Low pressure alone usually means a clogged aerator, a closed valve, or a failed regulator. If you suspect a leak, check your water meter: turn off all water in the house, wait 30 minutes, and check the meter again. If it has moved, you have a leak and should call a plumber.