Building Inspection, Diagnosis & Repair Info

Water pressure regulator control (C) Daniel FriedmanWater Pressure Regulator & Pressure Reducing Valve

How to diagnose and fix or replace a bad water pressure regulator.

This article describes Diagnosing a Bad Water Pressure Regulator - how to diagnose the loss of water pressure and the need for a replacement water pressure regulator. The process of water pressure problem diagnosis and the costs of the repair are explained.

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Water Pressure Regulator / Pressure Reducing Valve Failures

Water pressure regulators are devices that protect building plumbing systems from excessive water pressure damage by reducing incoming high water main pressure (that can be more than 150 psi in some communities) to a safe level (typically 50 psi) in the building.

Our photo at the top of this article shows typical incoming municipal water piping at a building.

From left to right we see a main water shut off valve, a water meter (wires lead to an outdoor water meter reading device), a water pressure regulator, and water piping rising into the building.

Article Contents

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Water is leaking at the water pressure regulator

Watts LF25AUB-Z3 water pressure regulator with detailed drawing of working parts, annotated by InspectApedia.comI came home today to a basement level laundry room floor covered in water. I hunted the leak: first thing I checked were the hot/cold water hoses for the washer as I just got a new one. It's not leaking.

Then I noticed the wall under the stairway is wet and now I can hear water spraying out of the water pressure regulator on my main water inlet line.

The regulator is spraying water out of the back. Huh? What? Anyone know what could cause this? On 2017-11-29 by kelz

Solution by (mod) - common causes of water pressure regulator leaks

I can't say exactly what is broken from your note Kelz but it sound as if your incoming water main is leaking at the regulator body. Some water pressure regulators incorporate a safety pressure relief valve but those are not commonly found on a single family home.

Shown here are the working parts of a typical residential type water pressure regulator from Watts, the Series LF25AUB-Z3 that is intended to set house water pressure beween 25-75 psi (172 - 517 kPa) and that can handle in incoming water pressure of up to 300 psi (20.7 bar).

We added the blue color to show the water passage through this device. You can see that since the water is in contact with the EPDM disc, if that material tears the regulator might indeed leak.

A common leak point at a water pressure regulator is at the pipe connections to the regulator itself at its inlet or outlet side.

It's possible that the EPDM pressure diaphraghm inside the regulator has torn or burst. That's a common cause.

The water pressure regulator diaphraghm is a thin disc of EPDM rubber that can crack or tear from age, water hammer, or unusual pressure surges from a municipal water supply main.

See details at WATER HAMMER NOISE DIAGNOSE & CURE

Less likely is that debris or sediment clogged the regulator so that it could not properly adjust output water pressure, leading to a leak.

Also less likely is that the regulator is leaking due to corrosion or rust.

Watch out: In any case you'd want to turn off the water main valve right away to stop the leak,

Then you might also open a nearby faucet to relieve water pressure in your house piping so that there wont' be more back-leakage out of your water pipes into the basement,

and then call your plumber for repair.

Causes of Variation in Building Water Pressure

This question is discussed in detail at WATER PRESSURE VARIATION CAUSES - below is a simplified summary

Diagnose Poor Municipal Water Pressure & Flow in a Building - 5 Key Checks

This topic has moved to its own page at MUNICIPAL WATER PRESSURE DIAGNOSIS 

Adjust the Water Pressure Regulator or Pressure Reducing Valve on Municipal Water Supply?

Details about how to adjust the building water pressure regulator or pressure reducing valve are found

at WATER PRESSURE REGULATOR ADJUSTMENT.

Watch out: don't set the water pressure reducing valve higher than necessary. Doing so wastes water and as we discuss

at WATER PRESSURE TOO HIGH: DANGERS, setting water pressure too high can cause both plumbing problems and actual serious safety hazards at buildings.

Adjust or Repair the Water Pump Pressure Control Switch (Private Pump and Well)

For details about diagnosing poor well water pressure and flow, start at WELL WATER PRESSURE DIAGNOSIS or go directly to the individual items listed just below.

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Continue reading at WATER PRESSURE REDUCER / REGULATOR or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER PRESSURE REGULATOR FAILURE FAQs - questions & answers about bad pressure regulators posted originally on this page.

Or see these

Recommended Articles

Suggested citation for this web page

WATER PRESSURE REGULATOR BAD at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER SUPPLY, PUMPS TANKS WELLS

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