The symptoms people call about
Water hammer, a bang in the wall when the washer or a faucet shuts off. Toilet fill valves that keep failing. The water heater relief valve dripping into the pan for no obvious reason.
Any of those on their own can be a part failure. Two or three together almost always means pressure.
How to check it yourself
Buy a screw on pressure gauge, thread it onto an outdoor hose bib with everything in the house off, and open the bib. Anything from 40 to 70 psi is healthy. Over 80 psi is above code and is what breaks fixtures.
Check again late at night. City pressure often climbs when neighborhood demand drops, so a house that reads 75 in the afternoon can be running 100 at 2 a.m.
The fix
A pressure regulator on the main handles it. Most homes here already have one near the front hose bib, and they wear out in roughly 8 to 12 years, so a high reading often means replacing an existing regulator rather than adding one.
If your water heater is closed off by a check valve or regulator, an expansion tank goes in at the same time so heated water has somewhere to expand instead of pushing the relief valve open.
Need a hand with this? See our leak detection & slab leaks page, or call 626-386-9105.