Is Your Water Pressure Too High? California's 80 PSI Rule

California plumbing code requires a pressure regulator — a pressure-reducing valve, or PRV — whenever the water pressure coming in from the street is higher than 80 psi. The regulator sits where the main water line enters the house, usually near the main shutoff, and lowers the incoming pressure to a safe household level, typically around 50 to 60 psi. When a regulator fails open, full street pressure reaches everything in the house, and the damage is slow and easy to miss: pipes that bang when a faucet shuts off, toilets that run on their own, fixtures that start dripping, and water heaters and appliances that wear out early. Over time, sustained high pressure also contributes to pinhole leaks and slab leaks. You can check your own pressure with an inexpensive gauge threaded onto an outdoor hose bibb. If the reading is over about 80 psi, have the regulator looked at.

What does a pressure regulator do?

A pressure regulator is a spring-loaded valve with an adjustment screw. Water from the city main arrives at whatever pressure the system delivers to your street; the regulator knocks it down to a steady, safe level before it reaches your pipes, fixtures, and appliances. It's usually found near the main shutoff where the water line enters the house.

Not every house has one. California requires one when the incoming pressure is over 80 psi.

What are the signs your water pressure is too high?

High pressure rarely announces itself. It shows up as a pattern of small problems that seem unrelated:

• Banging or hammering pipes when a faucet or appliance valve shuts off.
• Toilets that run or refill on their own.
• Faucets and fixtures that start dripping, sometimes several at once.
• Appliances and water heaters that fail early.
• Pinhole leaks that keep turning up in different places — and, over time, slab leaks.

If you're seeing two or three of these together, the pressure is worth testing before you repair each problem one at a time.

How do I test my home's water pressure?

Thread a water pressure gauge onto an outdoor hose bibb, make sure nothing else in the house is running water, and open the bibb fully. The needle shows your static house pressure.

• Around 50–60 psi: a normal, safe range.
• Over about 80 psi: too high. Either the house has no regulator, or the one it has has failed.
• Low, or jumping around: the regulator may be failing in the other direction.

What if my water pressure is too low?

A regulator can also fail closed, which starves the whole house — weak flow at every fixture, not just one. Pressure that swings up and down is another sign a regulator is on its way out. Low pressure at a single fixture is usually that fixture (a clogged aerator or cartridge), not the regulator.

Should a pressure regulator be repaired or replaced?

Usually replaced. Rebuild kits exist, but a new regulator is the durable fix. After it's installed, the regulator is set to the right pressure and checked with a gauge.

Why does a new regulator sometimes need an expansion tank?

A regulator turns your plumbing into a “closed” system — water can no longer push back into the city line. When your water heater heats water, that water expands, and on a closed system it has nowhere to go, so pressure spikes every time the heater runs. That's why installing or replacing a regulator often comes with an expansion tank requirement: the tank gives the expanding water somewhere to go. It's also why a dripping water heater relief valve is often a pressure problem, not a water heater problem.

More on water heater code requirements →

Common questions

What's a normal water pressure for a house?

Around 50 to 60 psi is a safe, normal range for most homes.

Is a pressure regulator required in California?

Yes, when the incoming water pressure from the street is higher than 80 psi.

Can high water pressure cause a slab leak?

It contributes. Sustained high pressure stresses pipes and joints and is a common factor behind pinhole leaks and, over time, slab leaks. If you're dealing with repeat leaks, test the pressure.

How we find hidden leaks →

Where is my pressure regulator?

Usually near the main water shutoff, where the main line comes into the house — often at the front of the house or in the garage.

Reading over 80 psi, or chasing leaks that keep coming back? We test the pressure, replace the regulator, and set it to spec. Call (805) 788-8444.