High Water Pressure in the House? How to Check It

How do I know if my water pressure is too high?

Put a gauge on it. A hose bib pressure gauge screws onto an outside faucet or the laundry standpipe, and any hardware store carries one. Shut off every fixture inside, open the bib all the way, and read the dial. That number is static pressure, what the house sits at when nothing is running.

Read it twice. Once in the evening and once late at night, because street pressure climbs when the neighborhood stops drawing water. A house that shows a calm 70 psi at dinner can sit at 95 psi at two in the morning, and that second number is the one doing damage.

Between 45 and 60 psi is where you want to land. That is the range EPA WaterSense recommends for incoming service pressure. Up to about 70 is livable. Over 80 is a problem, and 80 is also where the code draws its line.

What does California code say about 80 psi?

California Plumbing Code section 608.2 is short. Where static water pressure exceeds 80 psi, an approved pressure regulator with a strainer ahead of it has to be installed and the pressure brought down to 80 psi or less. That regulator belongs to the house, not to the water district.

Our local districts write the same rule into their service conditions. Marin Municipal Water District puts it on the customer: a pressure regulating valve has to be installed and maintained by the consumer if static service pressure exceeds 80 psi, and set to a maximum operating pressure of 60 psi at the regulator outlet. The City of Santa Rosa water distribution design standards allow static pressure in the system to run as high as 120 psi and require an individual pressure regulating device on any service over 80 psi.

So if your house sits below a tank in Fairfax, Mill Valley, or on the east side of Santa Rosa, high street pressure is normal and nobody is going to fix it for you. Knocking it down inside the house is your job.

What does high water pressure break first?

It usually does not announce itself with a burst pipe. It shows up as a list of small annoyances that all trace back to the same cause:

• Toilet fill valves that cycle on and off through the night.
• Faucet cartridges that start dripping a year after you replaced them.
• Pipes that bang when the washing machine or an irrigation valve shuts.
• The temperature and pressure relief valve on the water heater dribbling into the drain pan.
• Braided washing machine and dishwasher hoses that let go, usually while nobody is home.

The EPA sheet says it plainly: high water pressure damages piping, fixtures, and appliances, and leads to increased water consumption, premature equipment failure, and risk of leaks. Dripping cartridges and running fill valves are a faucet and fixture repair call, but swapping the part without fixing the pressure just restarts the clock on the next one.

Why is my water heater relief valve dripping?

This one catches people. Once a regulator or a backflow device goes in, the house becomes a closed system. Water can no longer push back out toward the street. Heat the tank and the water expands with nowhere to go, pressure spikes on every heating cycle, and the relief valve does its job and lets some out.

The fix is not a new relief valve. It is a thermal expansion tank, a small bladder tank on the cold inlet that gives the expansion somewhere to go. The EPA guidance tells installers to check whether thermal expansion needs addressing any time a regulator creates a closed system, and California requires one on closed systems. On our jobs an expansion tank runs $150 to $450 installed. If a relief valve is discharging, get it looked at instead of capping it. Start with water heater repair or the walkthrough at water heater leaking from the bottom.

How long does a pressure regulator last?

Ten to fifteen years is typical, and they fail in two directions. A regulator that fails closed starves the house, which is the low water pressure complaint most people call about. A regulator that fails open stops regulating at all and hands the house whatever the street is sending. The second one is quieter and costs more, because nothing actually stops working. It just all wears out early.

If the bell shaped brass fitting where the main line enters your house has never been touched since the place was built, it is past due no matter what the gauge reads today. While you are down there, look at the pipe itself: a wet spot around the meter or a meter dial that creeps with everything off points at the water service line, not the regulator.

What does it cost to fix?

Replacing a failed regulator runs $250 to $600 installed on most Sonoma and Marin homes, and that price includes setting the new one to a healthy 50 to 60 psi and rechecking it under load. Add $150 to $450 if the house needs an expansion tank and does not have one. Both numbers are small next to the drywall and flooring bill from a supply hose that let go at 100 psi with nobody home.

Fall is a sensible time to check it. Summer irrigation is coming off, so the house sits at static pressure more hours of the day, and this is the stretch to catch a tired supply line before the rain and the holidays. If your gauge reads over 80, or a line already let go, call CNTRline at (707) 308-5599. Quotes are free, and if water is coming out of somewhere it should not be, that is an emergency plumber call. We answer 7 days a week.