7 Reasons Your Water Pressure Is Low

Is the water pressure in your home not what it used to be? Low water pressure can be frustrating, but it can also indicate a more serious problem with your home’s plumbing system. First, you’ll want to determine if your water pressure is low at just one fixture or throughout the entire house. You may want to check in with your neighbors, too, to see if their water pressure has changed as well. Armed with this information, you can begin to determine the cause of low water pressure.

As a landlord, one of my more frequent calls from tenants involves low faucet water pressure. Thankfully, this is an easy fix that I can manage quickly. Unfortunately, not all causes of low water pressure are so simple. Read on to learn why your water pressure may be low as well as possible DIY fixes with tips from licensed plumber Liam Hogan.

Reasons Your Water Pressure May Be Low

Possible causes for low water pressure range from mundane to serious.

Obstructed Pipes

Over time, plumbing pipes can become clogged by debris, mineral build-up or corrosion. As the pipes narrow, water can’t move as quickly through them, resulting in lower water pressure. “This is especially true if you have hard water or galvanized pipes,” Hogan says. The best fix for this issue is to call a plumber to diagnose and replace any obstructed pipes.

Leaks in the Plumbing System

If there’s a leak in a water supply pipe, you may experience lower water pressure throughout the home. The break in the line allows water, but also pressure, to escape from the plumbing system. “There can be an obvious leak gushing water into your basement or a subtle, small leak under a bathroom sink,” Hogan says. Do some investigating, checking around all plumbing fixtures for damp areas, puddles or the sound of dripping or hissing water.

Faulty Pressure Regulator

If your home is equipped with a pressure regulator, and you’re experiencing low water pressure, a faulty unit may be to blame. Check that the regulator is set to 45 to 60 psi, a typical residential pressure setting. If it’s set lower than this, adjust the pressure accordingly. If this still doesn’t fix the problem, a broken regulator may be at fault. Call a licensed plumber to install a new one.

Undersized pipes

Pipes that are too small for the water supply demands of your home can cause water pressure to be less than desirable. Usually, water is supplied into the house in 3/4 to 1-in. pipes, then distributed through 1/2-in. branch pipes. If the main supply pipe is too small, this will reduce the water volume, which also reduces the pressure. This issue is exacerbated if plumbing demands increase due to an addition or new bathroom and the pipes are not resized.

Partially Closed Shutoff Valve

If your low water pressure is limited to one fixture, the shut-off valve may have become partially closed. Check the valve and make sure it is completely open. Also check the shut-off valve at the main plumbing line into the home. This is usually found in the basement, near the street. “If the main line valve is partially closed it will impact the water pressure all through the home,” Hogan says.

Water Supply Issues

Occasionally, your municipal water supplier is experiencing water supply issues themselves. If you check with your neighbors, and they have low water pressure as well, this may be the cause. Contact your water supplier to report the issue and receive any updates as they work to fix it. It is also possible that your city or town has changed their water regulations, maybe due to drought conditions, and the water supplier is only complying with the new rules. In this case, consider using high-pressure fixtures for higher water pressure.

Clogged or Faulty Fixtures

Sediment and debris in pipes can accumulate within fixtures, which will lower water pressure. Faucet aerators are especially susceptible to this issue, but are easy to fix. Unscrew the faucet end where the water exits and remove the small screen inside — this is the aerator. Gently clean it with soap and water, then replace it and tighten the faucet end.

In the shower, sediment can clog the shower cartridge. “If this is the case, it’s best to have a new one installed,” Hogan says.

FAQ

Is low water pressure dangerous?

It can be, depending on the reason your water pressure is low. If the cause is a leak somewhere in your plumbing system, you’ll want to catch this quickly before it causes major water damage. Even a minor leak can lead to property damage and mold growth.

What does it mean if my water pressure gets low suddenly?

If the water pressure drops suddenly throughout the house, this is most likely an issue with the pressure regulator, a clog in the main supply pipe or a water supply issue.

What does it mean if only my hot water pressure is low?

A partially closed hot water shut off valve is probably the cause. Check to make sure it is fully open. Other causes could be a faulty tempering valve that mixes hot and cold water within the fixture or an issue with your hot water delivery system. “You may need to have the hot water heater flushed to remove sediment build up,” Hogan says.

About the Expert

Liam Hogan owns Hogan Mechanical Incorporated in Agawam, Massachusetts. He holds a journeyman plumbing license and has five years of experience.