What Causes High Water Pressure in Phoenix Homes?

High water pressure in Phoenix homes is usually caused by a failed or missing pressure reducing valve, the brass regulator that sits where your water line enters the house. City pressure in parts of the Valley runs well above what household fixtures are built for, and when that valve wears out, full street pressure goes straight into your pipes.

We wrote about the opposite problem in why is my water pressure so low in Phoenix. This post is for folks whose faucets blast, whose pipes bang, and whose toilets won't stop running.

How Much Pressure Is Too Much?

Most homes do best between 50 and 70 psi. Plumbing code calls for a pressure reducing valve, or PRV, when street pressure is above 80 psi. Some Phoenix neighborhoods, especially near big supply mains, see 100 psi or more at the meter.

That pressure doesn't feel dangerous. A strong shower feels great. But every fitting, supply line, valve and appliance in your house is taking that pounding 24 hours a day.

Signs of High Water Pressure

Here's what we see on calls across the Valley:

• Pipes that bang or knock when a faucet or the washer shuts off, called water hammer
• A toilet that runs or refills on its own
• Faucets and shower heads that drip even after new cartridges
• Washing machine or dishwasher hoses that fail early
• A water heater relief valve that drips
• Sprinkler heads that mist instead of spray

You can check it yourself. Pick up a pressure gauge that threads onto a hose bib at any hardware store, screw it onto an outside spigot with everything inside turned off, and read it. Anything over 80 psi needs attention. Anything over 70 is worth watching.

Why PRVs Wear Out Faster in Phoenix

A PRV has a spring, a diaphragm and a seat inside. Our hard water, often 16 to 20 grains per gallon, builds scale on all three. Over time the valve sticks open or creeps, and the pressure slowly climbs. Around here a PRV often lasts 10 to 15 years, sometimes less. A lot of homeowners don't know they have one, so it never gets checked.

Some older homes never had a PRV installed at all. If your house went in before the pressure in your area changed, you may be running straight off the main.

A Call That Started With a Running Toilet

One of my techs took a call last summer from a family in north Phoenix who had replaced the flapper in their toilet twice in a month. It kept running anyway, so they figured the toilet was junk.

He put a gauge on the hose bib and it read 118 psi. The PRV near the front hose bib was original to the house and had stuck wide open. The toilet fill valve was fighting pressure it was never built for. We replaced the PRV, set the house to about 60 psi, and the toilet stopped running that afternoon. The banging pipes they'd learned to ignore went quiet too.

When High Pressure Isn't the Real Problem

Not every banging pipe is a pressure problem. Loose pipe straps in the attic or walls can knock even at normal pressure. A single dripping faucet may just need a cartridge. And if your pressure reads fine at the hose bib but spikes after you run hot water, the cause may be thermal expansion from the water heater, not the street.

That's why we test before we replace anything. Our 40-point plumbing inspection checks pressure, the PRV, the water heater and every fixture, so you fix the cause and not just the symptom. If high pressure has already caused a hidden leak, our leak detection and repair team can find it without tearing up your walls.

Get Your High Water Pressure Checked

Phoenix Plumbing Co. has been family-owned since 2012, now three generations strong, and our upfront flat-rate pricing means you see the price before we lift a wrench. Our trucks carry PRVs and gauges, so most pressure problems are fixed on the first visit, and every job comes with a written workmanship warranty. Call 602-834-1208 to talk with a live Phoenix dispatcher, or visit our homepage to learn more about our residential plumbing in Phoenix. High water pressure is one of the easiest plumbing problems to fix and one of the most damaging to ignore.