Why Is My Water Pressure Low? Causes and Fixes

Weak water pressure makes showers frustrating and slows down everything from filling a pot to running the washing machine. The good news is that many causes are simple, such as a clogged aerator or a valve that wasn’t fully reopened after a repair. Some, like a failing pressure regulator, corroded pipes, or a hidden leak, need more attention. This guide helps you narrow down the cause, try the fixes that are safe to do yourself, and recognize when it’s time to call a plumber.

Start by Narrowing It Down

The fastest way to find the cause is to notice where and when the pressure is low. Run a few fixtures and ask yourself these questions:

Is it one fixture or the whole house? One weak faucet or shower usually means a problem at that fixture. Low pressure everywhere points to the main supply, the pressure regulator, a whole-house filter, or the pipes.
Is it hot water, cold water, or both? If only the hot side is weak, look at the water heater and its valves. If both are weak, the problem is upstream of the water heater.
Did it happen suddenly or gradually? A sudden drop often follows plumbing work, a utility repair, or a new leak. A slow decline over months or years suggests mineral buildup, corroding pipes, or a wearing pressure regulator.
Are your neighbors affected? If they also have low pressure, the cause may be on the water utility’s side.

Common Causes of Low Water Pressure

Clogged aerators and showerheads

Faucet aerators and showerheads have fine screens that catch sediment and mineral scale. This is the most common reason a single fixture loses pressure, especially after the water has been shut off for repairs, which can loosen debris in the pipes.

A valve that isn’t fully open

The main shutoff, the valve at the meter, or a fixture’s supply (angle stop) valve may have been partly closed during a repair and never fully reopened. A gate valve with a round handle is fully open when turned all the way counterclockwise. A ball valve with a lever handle is open when the lever is parallel to the pipe.

A failing pressure-reducing valve (PRV)

Many homes on city water have a pressure-reducing valve near where the main line enters the house. Its job is to keep incoming pressure at a safe level. As a PRV wears out, it can cause low pressure, high pressure, or pressure that fluctuates. Not every home has one, so check near the main shutoff, typically a bell-shaped brass valve with an adjustment screw on top.

A clogged whole-house filter or water softener

Sediment filters and softeners sit on the main line. A filter cartridge that is overdue for replacement, or a softener with a problem, can restrict flow to the entire house. Most have a bypass valve. If pressure improves with the bypass engaged, you’ve found the cause.

Corroded or scaled pipes

Older galvanized steel pipes corrode from the inside, gradually narrowing the opening. Rusty or discolored water and a slow decline in pressure over years are classic signs. Hard water can also build up scale in pipes and fixtures over time.

Hidden leaks

Water escaping through a leak, whether under a slab, in a wall, or in the yard, can lower the pressure that reaches your fixtures. Leaks also waste water and can cause damage that isn’t visible for a long time.

Water heater issues (hot side only)

If only the hot water is weak, check that the cold supply valve to the water heater is fully open. Sediment in the tank or a problem with the heater’s fittings can also restrict hot water flow.

Well system problems

If your home uses a private well, low pressure often traces to the pressure tank, the pressure switch, a clogged sediment filter, or the pump. The well system’s settings and the tank’s air charge both affect your pressure.

Utility supply problems

Main breaks, repairs, and periods of high demand can temporarily lower pressure. Homes at higher elevations or at the end of a supply line may simply receive lower pressure than others.

Step-by-Step Fixes You Can Try

Clean the aerator or showerhead. Unscrew the aerator (wrap it in a cloth if you need pliers so you don’t scratch the finish), rinse out debris, and soak scaled parts in white vinegar for an hour or more. Scrub with an old toothbrush, rinse, and reinstall. Replace parts that are cracked or heavily scaled.
Check every valve in the path. Confirm the main shutoff, the meter valve if you can reach it safely, and the fixture’s angle stops are all fully open.
Test your water pressure. An inexpensive pressure gauge screws onto an outdoor spigot or a washing machine valve. With no water running in the house, read the static pressure. Many homes run between about 40 and 60 PSI. Testing at a spigot near where the main enters the house helps you tell whether the problem is coming into the house or happening inside it.
Check for leaks with your water meter. Turn off every faucet and water-using appliance, then look at the meter. Most have a small leak indicator (a triangle or small dial). If it is moving while nothing is running, water is going somewhere. Turn off the main shutoff: if the meter stops, the leak is inside the house; if it keeps moving, the leak may be between the meter and the house.
Bypass the filter or softener. If you have whole-house treatment equipment, use its bypass valve and compare pressure. Replace the filter cartridge if it’s due.
Adjust the PRV carefully, if you have one. Most PRVs have an adjustment screw under a cap on top. Loosen the locknut and turn the screw clockwise in small increments (a quarter turn at a time) to raise pressure, then recheck with your gauge. If adjusting doesn’t change the reading, or the pressure won’t stay steady, the valve likely needs replacement.
Flush the lines after plumbing work. After the water has been shut off, remove the aerators and run the faucets for a minute to clear loosened sediment before reinstalling them.
Contact your water utility. If your gauge shows low pressure at the spigot nearest the main and your valves are open, ask the utility whether there is work in your area or what pressure they normally supply.

When to Call a Plumber

Pressure is low throughout the house and the valves, aerators, and filters check out.
Your meter shows a leak you can’t find, or you suspect a slab leak (warm spots on the floor, the sound of running water, unexplained damp areas).
The PRV doesn’t respond to adjustment or needs to be replaced.
You have galvanized pipes with discolored water and declining flow. Repiping is a job for a licensed plumber.
Low pressure started after the meter or main line was replaced, and the utility says its side is fine.
Your well pump, pressure switch, or pressure tank needs service. That work involves electrical components.

DIY vs. Professional: A Quick Guide

Cleaning aerators and showerheads, checking valves, testing pressure, reading the meter, and changing filter cartridges are all reasonable DIY tasks with basic tools. Small PRV adjustments are often manageable for a careful homeowner. Replacing a PRV, finding and repairing hidden leaks, repiping, and well equipment repairs usually call for a licensed plumber or well contractor, and some may require a permit.

How to Prevent Low Pressure Long Term

Clean aerators and showerheads a few times a year, more often with hard water.
Replace whole-house filter cartridges on the manufacturer’s schedule.
Flush your water heater about once a year to limit sediment.
Check your water pressure with a gauge once or twice a year so you notice changes early.
Know where your main shutoff and PRV are, and exercise the main shutoff occasionally so it doesn’t seize.
If you have old galvanized plumbing, plan an upgrade to copper or PEX before it fails.

Frequently Asked Questions

What is normal household water pressure?

Many homes operate between about 40 and 60 PSI. Plumbing codes commonly require a pressure-reducing valve when incoming pressure is above 80 PSI, because very high pressure stresses pipes, fixtures, and appliances.

Why is my water pressure low in only one faucet?

It’s usually the aerator, a partly closed supply valve under the sink, or a worn faucet cartridge. Clean the aerator first, then check that the valves under the sink are fully open.

Why is only my hot water pressure low?

Check that the cold supply valve on the water heater is fully open. If it is, sediment in the tank or a restriction in the heater’s fittings or the hot-water piping may be the cause, and a plumber can help find it.

Can a water softener cause low water pressure?

Yes. A clogged resin bed, a problem with the control valve, or an undersized unit can restrict flow. Put the softener in bypass to see if pressure returns, and service it if it does.