Why is my house water pressure too high?

Answer

High water pressure in your home is typically caused by a malfunctioning pressure reducing valve (PRV), thermal expansion in a closed-loop system, or naturally high municipal water supply pressure. This can lead to leaks and appliance damage.

Roto-Rooter Plumbing & Water Cleanup
Last Updated:May 19, 2026

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Understanding High Water Pressure in Your Home

High water pressure is a common issue that can silently cause significant damage to your home's plumbing system and appliances. Identifying the cause is crucial for a lasting solution. The most frequent culprit is a failing pressure reducing valve (PRV), a conical device typically located near your main water shut-off. Its purpose is to lower incoming municipal water pressure to a safe level, usually between 40-80 PSI.

Common Causes of High Water Pressure

If the municipal water supply pressure is inherently high, a PRV is essential. Over time, these valves wear out, getting stuck open and allowing full street pressure into your home. Another significant factor is thermal expansion, especially in homes with a closed plumbing system and a water heater. When water heats up, it expands; if there's nowhere for this expansion to go, pressure builds up dramatically. Installing a thermal expansion tank can mitigate this issue by providing a buffer for the expanding water.

Risks Associated with High Pressure

Sustained high water pressure puts undue stress on pipes, fixtures, and water-using appliances. This can lead to premature failure of water heaters, washing machines, and dishwashers, as well as frequent leaks in pipes and faucets. It also contributes to noisy pipes (water hammer) and can inflate your water bill.

Situational Considerations for Water Pressure

Not all instances of high pressure indicate a faulty system. New construction or recent municipal water main work might temporarily increase pressure. Also, if you live at the bottom of a hill or in a high-rise building, your natural water pressure might be elevated. Certain types of specialized plumbing or fire suppression systems may also operate at higher pressures by design. Always consider your home's age and location.

Immediate Steps to Address High Water Pressure

  1. Purchase and install a water pressure gauge (available at hardware stores) on an exterior spigot to measure your current water pressure. This confirms the issue.

  2. Locate your home's pressure reducing valve (PRV), typically where the main water line enters your house. Check for signs of age or malfunction.

  3. Inspect your water heater area for an expansion tank. If absent and you have a closed system, consider adding one to absorb thermal expansion.

  4. Contact a qualified plumber to diagnose the exact cause of high pressure and recommend the appropriate repair, such as PRV replacement or adjustment.

  5. Familiarize yourself with local building codes regarding maximum allowable water pressure in residential properties, as these can vary by municipality.

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