Water pressure between 40 and 80 psi (pounds per square inch) is considered normal in a residential setting. A home inspector will typically measure water pressure by screwing a pressure gauge to an outdoor hose bib (faucet) and opening the valve. The pressure reading in the picture below comes in at about 62 psi, right in the middle of the desired range.
This is a good reading to see - not too high and not too low. Goldilocks would like this house.
Water pressure above 80 psi can lead to problems. Some washing machine and water heater warranties may be voided if hooked up to a house with high pressure. Flexible supply lines for washers can actually burst with high enough pressure.
Water pressure below 40 psi can be a problem if multiple plumbing fixtures are operating at the same time. Lower pressure means lower water flow and potential inconvenience to someone taking a shower while someone else flushes a toilet.
Brian Jovag, owner of Jovag Home Inspection.