In this article
Low water pressure has many possible causes, but a few minutes of checking narrows them down quickly. Start with one question: is the pressure low at one fixture, or everywhere?
First, narrow it down
- One faucet or shower only: the problem is at that fixture.
- Hot water only: the problem is at the water heater or its valve.
- The whole house: the problem is at the main valve, the pressure regulator, the pipes or the supply.
1. A clogged aerator or showerhead
The aerator is the small screen at the tip of a faucet. Mineral grit collects in it and chokes the flow. Unscrew it, rinse the screen, and soak it in vinegar if it is crusted. Showerheads clog the same way. This is the most common cause of low pressure at a single fixture, and it costs nothing to fix.
2. A valve that is not fully open
After any plumbing work, check the shut-off valve under the sink, the main valve where the water line enters the house, and the valve at the meter. A valve left half closed cuts pressure everywhere downstream of it. A round handle should be turned fully counterclockwise. A lever should sit in line with the pipe.
3. Old galvanized steel pipes
Many homes built before the 1960s, including a large share of the houses in Roseville, Warren and St. Clair Shores, were plumbed with galvanized steel. These pipes rust from the inside, and the rust slowly closes the opening until a three-quarter-inch pipe passes a trickle. The signs are pressure that has dropped gradually over years, pressure that falls sharply when two fixtures run at once, and a burst of rusty water after the house has been empty. The only lasting fix is to replace the galvanized pipe.
4. A failing pressure regulator
Some homes have a pressure-reducing valve, a bell-shaped fitting near the main shut-off. When it fails, pressure can drop or spike throughout the house, often quite suddenly. A plumber can test the pressure with a gauge and replace the valve.
5. A hidden leak
Water escaping through a leak never reaches your faucets. To check, turn off everything that uses water and look at the meter. If the dial or the small leak indicator is still moving, water is going somewhere. Other clues are a water bill that has climbed, a damp spot on a wall or ceiling, or the sound of running water when the house is quiet.
6. The water heater
If only the hot side is weak, look at the shut-off valve above the water heater first. Sediment in the tank and in the hot outlet can also restrict flow, especially in an older heater.
7. A problem with the supply
A water main break or work on the street can drop pressure for the whole block. Ask a neighbor. If theirs is low too, call the city water department before you call a plumber.
When to call a plumber
- Pressure dropped suddenly throughout the house and the neighbors are fine
- The meter moves when no water is being used
- You have galvanized pipes and the pressure gets a little worse every year
Common questions
Why is my water pressure low all of a sudden?
A sudden drop across the whole house usually points to a valve that was closed, a failed pressure regulator, a leak or a problem on the city side.
Why is the pressure low only in the shower?
Usually a clogged showerhead or a worn shower valve cartridge.
We track down pressure problems and replace old pipe across Macomb County. See our plumbing repair service or call (586) 943-4158 for a free estimate.
