Question About PSI?

I was speaking with a rep from the water company, and he told me that our water systems here in Riverside typically drive the water at about 100 to 115 PSI. He also told me that I really didn’t need a Water Pressure Reducer. My water is actually at about 90 PSI.

OK, I know that the plumbing world says 40 to 80 PSI. What say you?



Many manufacturers of faucet components will not warranty their products if water pressure is over 80 lbs. High pressure will cause water components to seep and/or leak. Wash machine and dishwasher cut-offs can be affected also with high pressure. Most cities will raise water pressure to service newer homes instead of building new pumps and/or water towers. I know checking pressure is over SOP’s, but checking it will solve many problems within home plumbing sytems. I suggest keeping home pressures to under 80. Any plastic water lines should have Watts reducing valves, but are not required in most cities. I check water pressure where possible, and note it on reports, and inform the buyer on how high pressure is not good, but high volume is.

California Plumbing Code requires a pressure regulator to be installed when the supply from the utility company exceeds 80 psi.

Ditto what Jeff said.

High pressure can cause lots of damage!!


I found one palce at 140 WOW!!

Are you saying you had a higher pressure downstream? You can’t have a higher pressure than what is available at the service meter unless you have a pressure tank and pump to increase your pressure. If the force main is delivering 115 psi at the road, you will not have a pressure higher than this in the house.

I think he was saying he had 140 PSI we are in TN Not CA High psi is a problem in some Area’s here.

My gauge said 140 psi
I can send you the picture if you like. There are not nearly as many regulations around here so water pressures can vary. I find 110 to 120 quite often.

I found 3 copper line leaks and someone had replaced the t and p valve on the water heater at the one with 140.

First of all, thanks for the responses. What the guy told me was that the water pumping station pumped at about 115 to 120. The reason was that it is pumping uphill. Now, here in California, are you guys telling me that if the pressure is over 80PSI, then a regulator is “Required”. By whom? The state? The local municipality? I see it in my Code Check book, but I’m not 100% sure where it’s required.

Next question. If the water from the water company is pumped at over 100 PSI, and a regulator is required, then doesn’t it stand to reason that the water company would put one in at the main? Why do they get to bypass the code, and I don’t? Should the original builder have done this?

You can see it’s quite a conundrum here. And last question, why is it code here in California, and not elsewhere. Aren’t the plumbing codes universal?

Thanks again.

I used to live in a community that had it’s water reservoir high up inside of a river bluff. There was about 100 PSI at the water main. No house regulators were required but you could only use type L copper and not the thinner type M.

Later I lived on lot where the water main pressure was above 80 PSI at my location and a regulator was required but there was no restriction on using type M copper.

I also had to have a sewer back water valve to prevent back ups into my basement in case the main below me on the hill became obstructed and the sewage above me had no where to go but up my floor drains.

The Code you are referring to is a Residential Building Code, the water Company has their codes to meet.

The water company is not required to regulate the pressure on individual homes, that is the Home Builders job. So the Home Builder should install a regulator on the water line before it enters the house.

The water company needs to supply a minimum water pressure to all the homes it serves.

As I said, it is the California Plumbing Code (CPC). Most of Riverside County follows the CBC, although the are some cities that have adopted portions of the IRC, all of which require regulators on supplies over 80 psi.

As Brian stated, it is not the utility company’s obligation to regulate their pressure, its the builders responsibility.

Jeff, Last question then. Would I find a regulator in the ground at the main, or would it have been installed at the house? I’m going to look this morning, but I suspect that the builder of my home did not install it. They cut as many corners as they could.

Again, thanks to all for the answers and comments.

I have seen them in the ground at the meter, but it’s much more common to have them mounted near the shutoff for the house. Regardless of where it is, it needs to be accessible, so it won’t be buried.

I am close to pumping station 115 lbs hurt to have a shower . Added a pressure reducing regulator now 40 lbs much nicer … Roys