Low water pressure in the whole house
Low water pressure in the whole house usually comes from a main valve that isn't fully open, a pressure-reducing valve that needs adjusting or has failed, or, on a well, the pressure tank or pressure switch. If only one faucet or shower is weak, the problem is at that fixture instead. A simple gauge that screws onto an outdoor faucet tells you in a minute whether the pressure is really low. A gauge on the outdoor faucet takes the guessing out of water pressure.
How water pressure is set
City water reaches the house at whatever pressure the street main carries, which can be well over 100 psi. Many homes have a pressure-reducing valve, a bell-shaped brass valve on the main line just after the , that lowers it to a steady level. Household pressure is commonly somewhere around 40 to 60 psi, and anything under about 40 psi usually feels weak.
On a private well, a pump fills a pressure tank, and a pressure switch turns the pump on when pressure drops to one setting and off at a higher one, such as 40 and 60 psi. Other causes apply to any home: a clogged whole-house filter or water softener, a hidden leak, and old galvanized steel pipes that slowly close up with rust from the inside.
Why the whole house has low pressure
Often left that way after plumbing work.
It holds pressure too low.
The whole house flows through it.
Lost water, rusted pipes or a worn switch.
| You notice | Likely cause | Start at |
|---|---|---|
| One shower or faucet is weak | A fixture problem | Step 1 |
| Only the hot water is weak | Water heater valve | Step 1 |
| Weak everywhere after plumbing work | Main valve partly closed | Step 3 |
| Gauge reads low with a PRV | Pressure-reducing valve | Step 4 |
| Pressure dropped after a filter change | Clogged filter or wrong cartridge | Step 5 |
| Meter moves with everything off | A hidden leak | Step 6 |
| Well pump runs often, weak flow | Tank or pressure switch | Step 7 |
| Weakest upstairs in an old house | Corroded pipes | Step 8 |
Let's fix it
- Make sure it's the whole houseTurn on the cold water at a few fixtures on different floors, then the hot. If only one shower or faucet is weak, the problem is at that fixture; there's a separate guide for low shower water pressure. If only the hot water is weak everywhere, look at the valve on the cold pipe into the water heater, which may be partly closed. If everything is weak, keep going.
- Measure the pressureThread a pressure gauge onto the outdoor faucet nearest where the water line enters the house, make sure no water is running anywhere inside, and open the faucet fully. Household pressure is commonly around 40 to 60 psi. A reading under about 40 psi confirms low pressure. Ask a neighbor whether theirs is low too, or call the water utility, since a problem in the street affects everyone.
- Open the main shutoff fullyFind the main shutoff where the water line comes in; we have a guide for finding your main water shutoff. A ball valve should have its handle lined up with the pipe; a round gate valve handle should be turned counterclockwise until it stops. Valves are often left partly closed after plumbing work or a meter swap. Leave the valve at the meter or curb to the water utility.
- Check the pressure-reducing valveLook for a bell-shaped brass valve on the main line just after the shutoff. Most have an adjusting screw on top with a locknut. Loosen the locknut, then turn the screw clockwise a quarter turn at a time to raise the pressure, checking the gauge after each turn, and keep it under 80 psi. Tighten the locknut when you're done. If turning the screw changes nothing, or the pressure drifts back down, the valve has likely failed and needs replacing.
- Check a whole-house filter or softenerIf there's a filter housing or water softener on the main line, it can be the bottleneck. Turn its bypass valve to bypass, or check the pressure before and after it. If pressure jumps with the filter bypassed, shut off the valve ahead of the filter, press the housing's pressure-relief button or open a faucet, unscrew the housing with its wrench, and replace the cartridge. A softener that restricts flow may need service.
- Look for a hidden leakTurn off every faucet and appliance that uses water, then watch the water meter. If the small leak indicator dial is spinning, or the reading changes over an hour, water is going somewhere. A big leak can lower pressure throughout the house. Check toilets, under sinks, the water heater, outdoor faucets and the yard between the meter and the house.
- On a well, check the tank and switchRead the gauge near the pressure tank as someone runs water. If the pump kicks on at a low pressure, the pressure switch may be set low or worn. With the pump's breaker off and the tank drained, check the air valve on top of the tank with a tire gauge; its air charge is typically set about 2 psi below the pump's cut-in pressure. The switch has live wiring under its cover, so leave adjustments to a well pro unless you're comfortable with the breaker off and the switch's instructions.
- Consider the pipesIn older homes with gray galvanized steel pipes, rust builds up inside and slowly narrows them. Pressure is usually worst on upper floors and at fixtures farthest from the main. Small fixes won't help much, and replacing the pipes is a job for a plumber.
- Call the right personIf the pressure is low right at the meter, call the water utility. If the pressure-reducing valve failed, the main valve won't open fully, the well equipment needs work, or the pipes are corroded, call a plumber or well contractor with your gauge readings in hand.
Watch it done
- The gauge reads about 40 to 60 psi
- Showers and faucets run strong
- The meter doesn't move with everything off
If it's just one fixture
If only one shower is weak, see the guide for low shower water pressure.
If only one faucet is weak, check our guide for cleaning a faucet aerator.
What a pro typically charges (a rough estimate; prices vary by area): A plumber typically charges $150–$300 for a pressure diagnosis or valve adjustment and $300–$700 to replace a pressure-reducing valve. A well pressure switch usually runs $150–$350 installed, and repiping a house with galvanized pipes often costs several thousand dollars.
Find a plumber near youSomething else going on?
Whole-house water pressure questions
Why is my water pressure low in the whole house?
Usually a partly closed main valve, a pressure-reducing valve that's set low or failed, a clogged whole-house filter, or a problem with a well's tank or switch.
What is normal household water pressure?
Commonly around 40 to 60 psi. Under about 40 feels weak, and over 80 is too high.
Can I adjust my pressure-reducing valve?
Usually, yes. Loosen the locknut and turn the screw clockwise in small steps to raise pressure, checking a gauge as you go.
How do I test my water pressure?
Thread a pressure gauge onto an outdoor faucet near the main line, make sure no water is running, and open the faucet.
Why do I have low water pressure everywhere?
Usually a main valve that isn't fully open, a pressure-reducing valve that needs adjusting or has failed, or on a well, the pressure tank or switch.