Water Pressure Too High: Signs, Testing, and How to Fix It
Most homeowners never test their water pressure. They should. Pressure above 80 PSI damages pipe joints, shortens appliance lifespans, causes water hammer, and accelerates water heater wear — all silently, over years. Here's how to test and fix it.
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Signs your water pressure is too high
- Water hammer. The banging sound when you quickly close a faucet or a dishwasher valve shuts. High pressure amplifies this and stresses pipe joints.
- Faucets and showerheads leak more than they used to. High pressure wears out valve seats and cartridges faster than normal. If you're replacing faucet cartridges every 1–2 years, pressure may be the culprit.
- Toilet fill valve constantly "running" briefly. The fill valve cycles on to top off the tank because the flapper is stressed by high pressure — even when it otherwise appears fine.
- T&P relief valve on water heater drips periodically. The temperature-pressure relief valve is doing its job — but high supply pressure is pushing it to open. You need an expansion tank and possibly a pressure reducing valve.
- Washing machine supply hoses fail prematurely. Rubber supply hoses on washing machines are rated for 80 PSI. At 100+ PSI, they can fail catastrophically — a leading cause of major water damage in homes.
How to test your water pressure
You need a water pressure gauge with a hose-bib fitting — available for $15–30 at any hardware store or on Amazon. The test takes two minutes.
- Step 1: Attach the gauge to an outdoor hose bib or a laundry sink faucet. Make sure no other water is running in the house.
- Step 2: Open the faucet fully. Read the gauge.
- Step 3: Normal residential pressure: 40–80 PSI. Recommended: 60–70 PSI. Over 80 PSI: needs attention. Over 100 PSI: urgent.
Test at different times of day — municipal pressure varies between peak morning hours and late night. The highest reading you get is what your pipes and appliances experience at worst.
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How to reduce high water pressure
Adjust the existing pressure reducing valve (PRV)
Most homes built after 1980 have a PRV — a bell-shaped device on the main supply line where it enters the house. There's an adjustment screw on top with a locknut. Loosen the locknut, turn the screw counterclockwise to reduce pressure, retighten. Test again. Adjust to 60–70 PSI. If the PRV doesn't hold a consistent setting or is over 10 years old, replace it.
Replace a failing PRV
A PRV that can't maintain a set pressure, or a home without one at all, needs a new valve installed. DIY cost: $50–100 in parts. Professional installation: $250–500. This is plumbing work that requires shutting off the main supply and soldering or connecting to the main line — doable for an experienced DIYer, better left to a plumber if you're not comfortable.
Install an expansion tank
If high pressure is specifically causing your water heater's T&P valve to drip, the pressure spike is from thermal expansion in a closed plumbing system. An expansion tank ($30–80) installed on the cold water inlet to the water heater absorbs the pressure spike. Often required by code when a PRV is installed.
Replace washing machine hoses
If you have high pressure and rubber washing machine hoses, replace them with braided stainless steel hoses immediately ($20–30 for a pair). This is the single highest-risk failure point for high-pressure homes and one of the cheapest fixes. Do it regardless of whether you address the underlying pressure issue.
Cost summary
| Fix | DIY Cost | Pro Cost |
|---|---|---|
| Pressure gauge (test tool) | $15–30 | — |
| Adjust existing PRV | Free (just a screwdriver) | $75–150 service call |
| Replace PRV | $50–100 | $250–500 |
| Expansion tank | $30–80 | $150–350 installed |
| Braided washing machine hoses | $20–30 | — |
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