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Low Water Pressure in Houses: What Causes It and What Fixes It

August 18th, 2021 | Plumbing

low pressure sink

Everyone has experienced that sad moment in the shower—expecting forceful streams of water to come out of the showerhead and getting only a slow-moving soak. Most of the time, it's an isolated incident: One of your family or housemates had the nerve to start the dishwasher at the same time as your shower.

But what happens when water from every plumbing fixture in your home slows down to a mere pour for continued days or even weeks? What causes low water pressure in the whole house?

Here’s a look at what causes low water pressure in a house. We’ll also discuss what steps you should take when you discover these issues and whether you should call a professional who knows how to fix low water pressure in a house or try DIY methods.

What Causes Low Water Pressure in the Whole House?

When you’re having low water pressure issues with just one faucet or tap, it’s usually because of a problem with that specific outlet (and theoretically easier to fix). But what about when you experience issues throughout the whole home?

Here are some of the issues that may be causing low water pressure in your house.

Valves Aren’t Open All the Way

Two separate valves work to control the flow of water throughout your home.

One is the master house shutoff valve, which you probably haven’t messed with unless you’ve had some sort of pipe emergency or leak. In most cases, it's found inside the house, close to the entry point of your local or city water supply, but it may be somewhere outside.

The other is the water meter valve belonging to your local water utility company. This valve is typically harder to find, often located underground. In addition, it’s almost always accessed only by the water company, so if you’ve had repairs on your water pipes in the recent past and are having water pressure issues, the serviceperson may not have opened the valve all the way.

Bad Pressure Regulator

Many, but not all, plumbing systems have regulators that control water pressure to prevent damage to your pipes. Unfortunately, a faulty regulator can make the water pressure in your home go to extremes—either high or low. It will be pretty easy to notice when this happens since it affects all water fixtures in the house.

Old or Corroded Pipes

Especially if you own an old house and haven’t replaced the pipes, your plumbing may need to be replaced. Pipes made from all materials eventually need to be switched out, but certain types need replacement sooner than others.

Galvanized steel pipes, for example, are very susceptible to corrosion. As a result, they only have an expected work span of 20 years or so. That's why steel is not used much in new plumbing systems anymore, but it may exist in older houses. Plumbing systems made of brass or copper can go between 40 and 70 years before corrosion ends their usefulness.

Leaking or Clogged Pipes

Leaks and clogs may seem like obvious causes of low water pressure in the house. If your pipes are leaking excessive amounts of water, then it stands to reason that your water pressure is lower. But it doesn't have to be a massive, basement-flood-sized leak—even minor leaks can create problems. Alternately, the pipes may be obstructed by dirt or debris, just as your sink or toilet gets clogged from time to time.

Shared Pipelines

In some neighborhoods, two or more houses may draw their water supply from the same pipe system. You may not be aware of this because it’s not reflected on your utility bill. But if your next-door neighbor starts a shower or a washing machine cycle, it could cause low water pressure in the houses nearby.

Changes in Local Water Policy

This scenario is rare but can happen in localities forced into situations, like droughts, which call for water rationing. If your city has decided to regulate water usage more closely, it may affect your water pressure and the amount of water you use.

How to Fix Low Water Pressure in Your House

With most serious water issues like low pressure, you’ll want to call a professional plumbing service. If you have problems with underground pipes and fixtures only the utility company can access, you will not even be able to attempt repairs on your own. There’s also the risk of damaging the pipes even further if you try to fix the problems yourself.

But there are ways you can do to get a better handle on what’s causing the problem before the plumber arrives and steps you can take to prevent low water pressure in the future.

Open the Master Shutoff Valve

Unless a plumber is repairing your master shutoff valve, there's no reason it needs to be less than 100% open. So, after you’ve figured out where this device is situated in your house, check to see whether the valve is open all the way. If it uses a rotating handle—like your garden hose does—turn it all the way counter-clockwise. If it has a lever or handles, then adjust it to parallel it to the pipe.

Find Out Your Home’s Repair and Water History

If your home’s more than 50 years old and you’ve never replaced the pipes, check your local city records to see if there’s a history of repair work at your address that you can look at. If they show the pipes are steel, it probably means they need replacement. Also, check with your water company or homeowner association to see if your house shares a pipeline with another neighbor.

Check for Leaks

Some pipe leaks are easier to detect. For example, you’ll find water damage or drips around the site of the leak. Underground leaks are harder to find. One common way to diagnose this is to shut your master valve off completely and check to see if the water meter’s still moving. If it’s moving fairly quickly, there’s a severe leak somewhere. (Don’t forget to open the valve all the way when you’re done.)

Test the Pressure Regulator (If You Have One)

If your home uses a pressure regulator, you can check it by attaching a pressure gauge to your garden hose spigot and reading the meter. If it shows a measurement of fewer than 52 pounds per square inch, it likely means the regulator needs to be upgraded or replaced.

If you have low water pressure in your house, call Moffett Plumbing & Air.

Moffett Plumbing & Air is a full-service, family owned & operated plumbing & HVAC company based out of Orange, CA. Follow our blog for valuable homeowner tips, and updates from your favorite team of plumbing professionals.