Why is my house water pressure too high?
Updated August 2026
If you screw a gauge onto a hose bib and it reads past 80 psi, the cause is almost always a failed or misadjusted pressure-reducing valve (PRV) where the city main enters the house, or a high-pressure municipal line that never had a PRV to begin with. Water utilities often push 100 to 150 psi to reach hilltop homes and fire hydrants, and the bell-shaped PRV on your main is supposed to knock that down to a house-friendly 50 to 60 psi. When it wears out or drifts, pressure climbs and quietly beats up every fitting, valve, and appliance in the plumbing. Confirm the number with a $10 gauge, then work down the list below.
Safety first: sustained pressure above 80 psi is not just an efficiency nuisance. It shortens the life of supply lines, washing-machine hoses, and the water heater, and it is the classic reason a faucet keeps dripping after you shut it off or a temperature-and-pressure relief valve weeps. A burst braided hose behind a washer can put hundreds of gallons on the floor in an hour, so if your gauge reads 90 psi or more, treat the PRV fix as urgent rather than optional.
Causes, most likely first
| Cause | How likely | The fix | Typical cost |
|---|---|---|---|
| Failed or misadjusted pressure-reducing valve (PRV) | Most common | Turn the adjustment screw down to reach 50–60 psi; if it will not hold, replace the valve. | $250–450 installed |
| No PRV on a high-pressure city line | Common | Have a plumber add a PRV where the main enters, plus a thermal expansion tank. | $300–500 |
| Thermal expansion with no expansion tank | Common | Pressure spikes only after the water heater runs; add or recharge a thermal expansion tank. | $40–200 part, $150–350 installed |
| Adjustment drift after years of service | Occasional | Readjust the PRV; a valve past 10–15 years usually needs replacing rather than tuning. | $250–450 |
| Faulty or misread gauge | Occasional | Verify with a known-good $10 gauge on a different bib before spending anything. | $10 |
Check these first
- Thread a $10 water-pressure gauge onto an outdoor hose bib or the washing-machine cold tap and read the static pressure with every fixture off.
- Take a second reading late at night; city pressure often peaks after midnight when demand drops, and that is when 80-plus psi does its damage.
- Look where the main enters the house for a bell-shaped brass PRV; no bell usually means no PRV is installed.
- Watch whether the pressure climbs only after the water heater fires, which points to thermal expansion rather than the PRV itself.
- Check the water heater temperature-and-pressure valve and any dripping faucets, since those parts complain first about high pressure.
Prevent it next time
A high-pressure problem is cheap to catch and expensive to ignore. Keep a $10 gauge in a drawer and test your pressure a couple of times a year, aiming for that 50 to 60 psi band and never letting it sit above 80. A PRV is a wear part: budget to replace it every 10 to 15 years before it fails wide open. You can dig into the appliance and fitting damage that unchecked pressure causes in our cost of high water pressure guide.
When to call a pro
Turning a PRV adjustment screw is homeowner-level work, but replacing the valve or adding one to a line that never had it means cutting into the main and is a job for a licensed plumber, typically $250–450 for a swap and $300–500 for a new install with an expansion tank. Call sooner if the pressure will not drop no matter how far you back off the adjustment, if the PRV body is leaking, or if you are seeing water hammer and banging pipes on top of the high reading. Those signal a valve that has failed internally.
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Stop chasing symptoms, free for 30 daysFrequently asked questions
What water pressure is too high for a house?
Anything steadily above 80 psi is too high, and most plumbing codes cap residential pressure right at that 80 psi line. The comfortable, appliance-friendly target is 50 to 60 psi. A little higher feels great in the shower but shortens the life of hoses, valves, and the water heater. If a $10 gauge shows 85 to 100 psi or more, you have a real problem to fix, not a preference to enjoy. Readings that swing widely between day and night point to a PRV that is losing its grip.
Can high water pressure damage my appliances?
Yes, and it does it quietly. Dishwashers, washing machines, water heaters, and ice makers all use small fill valves rated for normal household pressure, and a constant 90-plus psi wears their seals and solenoids out years early. High pressure is also the leading cause of a suddenly burst washing-machine hose, which can flood a floor before you notice. Dropping the pressure back to 50 to 60 psi with a working PRV is one of the cheapest ways to protect several thousand dollars of appliances.
Can I adjust the pressure-reducing valve myself?
Usually, yes. Loosen the lock nut on the PRV, then turn the adjustment bolt clockwise to raise pressure or counterclockwise to lower it, moving in small increments and rechecking the gauge until you land at 50 to 60 psi. Retighten the lock nut when done. If the valve will not respond, holds pressure too high no matter what, or leaks from the body, the internal seat is worn and the valve needs replacing rather than tuning. That swap runs about $250 to 450 with a plumber.
Why is my water pressure high only at night?
Municipal water systems run higher overnight because everyone stops drawing water, so demand falls and pressure in the main climbs. A healthy PRV holds the house at 50 to 60 psi around the clock. When you see 60 psi by day and 90 at night, the valve is no longer regulating well and is letting the overnight spike through. That is exactly when high pressure stresses fittings the most, so a late-night reading is the best single test of whether your PRV still works.