High water pressure and the pressure regulator
Banging pipes, dripping relief valves and short-lived faucet parts can all trace back to high water pressure.
Updated · 3 min read
In a nutshell
A pressure regulating valve (PRV) at the main line cuts street pressure down to a safe level for your house. If a hose-bib gauge reads well above the setting on your regulator, or your house has no regulator, a new or adjusted PRV protects every fixture.
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What a PRV does
Water mains have to push water uphill and across long distances, so pressure at the street can be higher than household fixtures like. A regulator on the line entering the house steps it down.
Most residential regulators are bell-shaped brass valves near the front hose bib or where the line enters the house, with an adjusting screw on top.
How to test your pressure
Buy a screw-on pressure gauge from a hardware store and thread it onto an outdoor hose bib near the regulator. Turn the bib on fully with everything inside off.
Read it in the morning and again late at night, when demand on the street is low. Night readings are often higher.
Signs pressure is too high
- Pipes bang when a valve closes quickly
- Toilet fill valves hiss or fail often
- The water heater's relief valve drips
- Faucets spray hard enough to splash out of the sink
Repair, adjust or replace
Some regulators simply need adjustment. A regulator that will not hold its setting, or lets pressure creep up overnight, has worn internal parts and is usually replaced.
After a regulator is installed, the house becomes a closed system, so we also check whether the water heater needs a thermal expansion tank.
Rosemead owners ask
Does every Rosemead house have a PRV?
No. Many older houses were built without one. Others have one that has been in place for decades.
Will a PRV reduce my shower pressure too much?
It is set to a comfortable household level, not a trickle. Good regulators keep pressure steady across fixtures.
Why does my relief valve on the water heater drip?
High house pressure or thermal expansion are common causes, so check pressure before replacing the valve.