Where the extra pressure comes from
City water systems are built so that homes at the highest elevations in a pressure zone still get usable pressure. That means homes lower in the same zone receive more. On rolling ground like Coyote Hills, two houses a short walk apart can sit at different elevations and see noticeably different readings at the hose bib.
Where incoming pressure is high, a pressure regulating valve is the normal defense. Problems usually start when that valve was never installed, was removed during a remodel, or has worn out and is passing street pressure through to the house.
What high pressure does over time
| Part of the house | What tends to happen |
|---|---|
| Toilet fill valves | Hiss, run or fail early; flappers may not seal |
| Washing machine and dishwasher hoses | Extra stress on hoses and connections; a burst hose can flood a room |
| Water heater | Relief valve drips or discharges; tank and connections are stressed |
| Faucet cartridges and valves | Drips, spitting aerators and early wear |
| Pipes and fittings | Banging when valves close; joints and supply lines take repeated shocks |
| Irrigation | Sprinkler heads mist or pop; valves and drip fittings blow apart |
Confirming it yourself
A simple screw-on gauge from a hardware store is enough for a first look.
- Pick the right spigot.Use an outside hose bib on the house side of the regulator, ideally the one nearest it.
- Turn everything else off.Make sure no sprinklers, appliances or fixtures are running so you see static pressure.
- Read and repeat.Open the bib fully and note the reading. Check again early in the morning and late at night, when demand on the street is lowest.
- Watch for creep.Leave the gauge on and come back later. A higher number with no use points toward a leaking regulator or thermal expansion.
What the reading suggests
- IfReading above 80 psi and no regulator existsThenAsk a licensed plumber about installing one; the plumbing code generally calls for it.
- IfReading above 80 psi with a regulator in placeThenThe valve may be failing or set too high. Have it tested before replacing other parts.
- IfReading normal by day, high by morningThenLook at thermal expansion and the expansion tank at the water heater.
- IfReading normal but one fixture misbehavesThenThe problem is probably at that fixture, not the incoming pressure.
Bringing it down and keeping it down
The usual fix is a properly sized regulator set to a sensible pressure, plus an expansion tank if the system becomes closed. Replacing worn fill valves, braided supply lines and washer hoses after pressure is corrected makes sense; replacing them before just means they wear out again.
Cost depends on whether a regulator already exists, how easy the main line is to reach, the pipe material at the connection and whether an expansion tank is added. Ask for each item to be listed on a written quote, and ask whether a permit applies. For permit questions, check with the City of Fullerton.
Common questions
Is high pressure good for showers?
It can feel stronger, but most fixtures are designed to work well within normal household pressure. A good shower head at proper pressure is easier on the whole system.
Can high pressure cause a slab leak?
Excess pressure adds stress to every pipe and joint, including lines under a slab. It is one factor among several, such as pipe age and water chemistry.
Why did my pressure change after city work on the street?
Work on the mains can change supply conditions. If neighbors notice it too, contact Fullerton's water utility. If only your home changed, have your regulator checked.
General information for Coyote Hills, not a quote or professional advice. In an emergency, call 911.