How to Test Your Home's Water Pressure

Water Pressure Gauge
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It’s a good idea to test water pressure in your home a couple of times per year as part of a plumbing maintenance checklist. Testing water pressure is quick and easy, and all you need is a simple and inexpensive pressure gauge. Some homes even have dedicated gauges hooked up somewhere in the water line so homeowners can check the water pressure quickly and easily with just a glance. But if you don't have a permanent gauge, it is very easy to do a periodic test with a standard water pressure gauge.

Why Test Your Home's Water Pressure?

Having too much water pressure can be hard on all plumbing lines and fixtures and can even cause blowouts in flex lines or washing machine hoses, which in turn can flood the house. It’s a good idea to test water pressure even if your home has a pressure regulator, or pressure-reducing valve, on the main water supply because it isn’t necessarily obvious when a regulator fails. Testing water pressure occasionally can catch a problem with the pressure regulator before the high pressure can damage any plumbing.

Tools and Supplies You Will Need

To test your home's water pressure, all you need is a pressure gauge that measures in psi (pounds per square inch). You can find these at most home centers and hardware stores. To make it really easy, get one with female hose threads so you will be able to screw this into a hose bib or washing machine bib.

You might also need a pair of tongue-and-groove pliers (a.k.a. Channel-Locks) or a large adjustable wrench to tighten the gauge onto the test faucet. However, in most cases, you can get the gauge sufficiently tight by hand.

If desired, you can keep a journal of test results to monitor changes in the water pressure over time.

Instructions

Choose the Testing Location

If your water comes from a city or municipal water utility, select an outdoor hose bib faucet (spigot) closest to where the home's main water supply line (from underground) enters the house. If you get your water from a well, use a faucet or fixture that is close to the well's pressure tank. You will get the most accurate reading if the test hose bib or faucet is fed by supply pipe that is the largest size inside the house as it has not been reduced like the supplies to bathroom plumbing fixtures, for example. This size is likely to be 3/4-inch, which is preferable, but it may be 1/2 inch.

Check for Running Water

To get an accurate reading when you test water pressure, make sure water isn’t being used anywhere inside or outside the house. Turn off washing machines, sprinklers, refrigerators with ice makers, and dishwashers. When you test the pressure with a gauge, you are measuring the static water pressure; if water is moving anywhere in your plumbing system, it may result in a falsely low reading.

Install the Pressure Gauge

Remove the hose from the faucet, if there is one connected; do not perform the test with a hose. Thread the pressure gauge onto the faucet. There will be a rubber gasket inside the pressure gauge, and you should be able to simply hand-tighten the pressure gauge and get a good seal. But if this connection leaks a little during the test, tighten it a bit more with tongue-and-groove pliers or an adjustable wrench because a good seal is necessary for an accurate reading.

Check the Pressure

Turn the faucet all the way, then read the pressure on the gauge's dial. Typical home water pressure ranges from 40 to 50 psi and generally should not exceed 60 psi. Most common pressure regulators have a maximum adjustment up to 75 psi, so if the reading on the pressure gauge is over 75 psi, then you know that the pressure regulator is not working correctly and will have to be repaired or replaced. If you don't currently have a pressure regulator installed and the water pressure reading is over 60 psi, consult a plumber about having a regulator installed.

Testing at the Washing Machine

An alternate place to test your water pressure is at your washing machine's cold water supply faucet. Shut off the cold water at the faucet behind the washing machine, then disconnect the hose from the faucet (be careful as it will be full of water). Screw the pressure gauge onto the faucet, then open the faucet all the way to test the pressure.