Start by finding where the pressure drops
Low water pressure throughout your whole house usually points to one of three problems: a closed valve, a clogged water line, or an issue with your water meter or main supply. Low pressure in only one room or fixture is almost always a clogged aerator or a valve someone turned partway shut. The first step is to figure out which one you have, because the fix is completely different.
Turn on a cold-water tap in your kitchen sink and feel the pressure. Then turn on a hot-water tap in the same sink. If cold water is weak but hot water is normal, the problem is in your cold-water line only — usually a clogged aerator or a valve. If both are weak, or if cold is weak everywhere in the house, you have a whole-house problem.
Next, check whether the pressure is low everywhere or just in one room. Turn on taps in your kitchen, bathroom, and laundry room. If only one room is weak, the problem is in that room's supply line or a valve serving that room. If everything is weak, move to the main water shutoff valve.
Key Takeaways
- Low pressure in one fixture usually means a clogged aerator, which you can clean by unscrewing the screen at the tap's end and rinsing it under running water.
- Low pressure everywhere in the house often means the main shutoff valve is partially closed — check that the handle points in the same direction as the pipe.
- If your pressure was normal yesterday and weak today, check for a burst pipe in your yard or basement before calling a plumber.
- Sediment buildup in your water heater can cause weak hot water only; draining the tank may restore pressure.
- A water pressure regulator that has failed will cause weak pressure throughout the house and usually needs replacement by a licensed plumber.
Check the main shutoff valve first
Your main water shutoff valve is usually in your basement, crawl space, or near the front of your house where the water line enters. It looks like a lever handle or a round knob on a pipe. If the handle is a lever, it should point in the same direction as the pipe — straight along it. If it points across the pipe at a right angle, someone has turned it partway shut, and that is why your pressure is low.
Turn the lever so it points along the pipe. If the handle is a round knob, turn it counterclockwise (the same direction you turn a faucet to open it). Turn it slowly — do not force it. After you have opened it fully, go back to your kitchen sink and turn on the cold water. Wait 30 seconds and check whether the pressure has improved.
If the valve is already pointing the right way and the pressure is still low, the problem is not a closed valve. Move on to the next section.
Clean aerators and screens on individual faucets
An aerator is the small screen at the end of your faucet. Over time, sediment and mineral buildup clog it, and water comes out weak. This is the easiest fix — it takes five minutes and costs nothing.
Unscrew the aerator by turning it counterclockwise by hand. If it is stuck, wrap a cloth around it and use pliers, but turn gently so you do not crack the chrome. Once it is off, hold it under running water and rinse it thoroughly. Use an old toothbrush to scrub away any white or brown buildup. If the screen is very clogged, soak it in white vinegar for 30 minutes, then scrub again.
Screw the aerator back on by hand, turning clockwise until it is snug. Do not overtighten. Turn on the faucet and check the pressure. If it is better, you are done. If it is still weak, the problem is in the supply line to that faucet, and you will need a plumber.
Look for leaks or burst pipes
If your pressure dropped suddenly — it was normal yesterday and weak today — check for a leak. A burst pipe in your yard or under your house will send water pressure down because water is escaping instead of flowing to your taps.
Walk around your yard and look for wet patches, soft ground, or areas where the grass is greener than the rest of the lawn. Check your basement or crawl space for water dripping from pipes or pooling on the floor. If you see water where it should not be, you have a leak. Turn off your main shutoff valve when ready and call a licensed plumber — a burst pipe needs professional repair.
If you do not see any obvious leaks, the problem is likely inside your water meter or main line, which a plumber will need to inspect.
Drain your water heater if hot water pressure is low
If your cold water pressure is normal but hot water is weak, sediment has probably built up inside your water heater tank. Over time, minerals settle at the bottom and clog the outlet. Draining the tank can restore pressure.
Turn off the power to your water heater — flip the breaker if it is electric, or turn the gas valve to "off" if it is gas. Wait 30 minutes for the water to cool. Attach a garden hose to the drain valve at the bottom of the tank and run the hose to a floor drain or outside. Open the drain valve by turning the handle counterclockwise. Let the water run until it runs clear, which usually takes 10 to 20 minutes. Close the valve, disconnect the hose, and turn the power back on.
Go to a hot-water tap and turn it on. The pressure should improve within a few minutes as the tank refills. If the pressure is still weak, the problem may be a faulty mixing valve inside the heater, and you will need a plumber.
Check for a failed pressure regulator
A water pressure regulator is a bell-shaped device on your main water line, usually near the shutoff valve. It keeps pressure from the street from getting too high and damaging your pipes. If it fails, pressure drops throughout the house.
Look for a regulator on the pipe coming into your house. It is usually brass or chrome and about the size of a fist. If you see one and your pressure is low everywhere, the regulator may have failed. You can try adjusting the screw on top — turn it clockwise a quarter turn and check the pressure. If that does not help, the regulator needs replacement.
Replacing a regulator requires turning off the main valve, unscrewing the old one, and screwing in a new one. This is a job for a licensed plumber unless you have experience with water line work. A new regulator costs between $150 and $300 in parts and labor, depending on your area.
When to call a plumber
Call a plumber if you have checked the main shutoff valve, cleaned all the aerators, found no leaks, and the pressure is still low. Also call if you see water pooling in your basement or yard, or if pressure dropped suddenly and you cannot find the cause.
Before the plumber arrives, write down exactly when the pressure dropped, which taps are affected, and whether the problem is cold water, hot water, or both. This information helps the plumber narrow down the cause. If you have a water meter, ask the plumber to check it — a faulty meter can cause low pressure, and the water company may replace it for free.
Frequently Asked Questions
Can low water pressure damage my pipes?
Low pressure itself does not damage pipes. However, if low pressure is caused by a leak, the escaping water can damage your foundation, yard, or basement. If you suspect a leak, turn off the main shutoff valve and call a plumber right away.
Why is my water pressure low only in the morning?
Morning low pressure is usually caused by high demand in your neighborhood — everyone is showering and using water at the same time. This is normal and should improve within an hour. If it happens all day, the problem is in your house, not the street supply.
Will a water softener fix low pressure?
A water softener does not fix low pressure, but it can prevent future clogs from mineral buildup. If you have hard water and low pressure, clean your aerators first. A softener helps only after the when ready problem is solved.
Is low water pressure a sign of a serious problem?
Low pressure is usually caused by something straightforward — a closed valve or a clogged aerator. However, if it appears suddenly and you cannot find the cause, it may mean a leak or a failing regulator. When in doubt, call a plumber to rule out expensive problems.
How much does it cost to fix low water pressure?
If the problem is a clogged aerator or a closed valve, the cost is zero. If you need a plumber to inspect the line or replace a regulator, expect to pay $150 to $400 depending on what is found and your location.