How to Fix a Leaky Backflow Preventer?

A leaky backflow preventer can be a nuisance to homeowners and pose potential risks to the water supply system. This crucial plumbing component keeps contaminated water from flowing back into your home’s clean water supply, so it’s essential to address any issues promptly.

In this blog post, we’ll explore how to identify and fix a leaky backflow preventer, discuss common causes of leaks, and provide valuable tips on maintaining your plumbing system for optimal performance.

If you want to find out more about what a backflow preventer is and why your home needs one, PlumbTech has all the resources you’ll need.

Identifying a leaky backflow preventer


To identify a leaky backflow preventer, look for signs such as water spraying or pooling around the valve or pressure relief valve, decreased water pressure in the irrigation system, or contaminated and/or discolored water coming out of faucets.

Signs and symptoms of a leaky backflow preventer

A leaky backflow preventer can cause various issues in your plumbing system and may even lead to water contamination, making it crucial for homeowners to be aware of the signs.

One common sign is the presence of water pooling around the backflow device, which suggests that there’s a leakage issue that needs immediate attention.

In some cases, you may hear unusual noises emanating from the backflow preventer itself, such as hissing or gurgling sounds – which could indicate trapped air or dysfunctional valves within the assembly.

It’s also good practice to periodically inspect your irrigation system for any irregularities like uneven watering patterns or flooding in specific areas, as these can hint at underlying issues with your backflow prevention device.

How to inspect the backflow preventer

To start inspecting a backflow preventer, you need to turn off the water supply and relieve any pressure from the system. Then, carefully examine all parts of the valve assembly for any signs of corrosion or damage.

Check for leaks around valves and connections using a flashlight if necessary.

Next, test each check valve present in your backflow prevention assembly by turning on your irrigation system and checking their proper operation- they should open only when water flows in one direction as intended.

By simply taking these steps, homeowners can easily identify most issues affecting their backflow preventer’s performance without requiring professional assistance.

Fixing a leaky backflow preventer


To fix a leaky backflow preventer, turn off the water supply and disassemble the valve. Then, carefully clean and replace any damaged parts before reassembling the valve and turning on the water supply.

Shutting off the water supply

Before you start repairing a leaky backflow preventer, it’s crucial to shut the water supply off first. This is a necessary step because it prevents further water damage and ensures your safety during the repair process.

To begin, locate the main water valve that supplies water to your home or business and turn it off. Once the valve is turned off, open any faucet in your home to drain any remaining water in the pipeline.

If you’re not sure where your main water valve is located or how you turn it off, consult a licensed plumber for assistance.

Disassembling the valve

To fix a leaky backflow preventer, disassembling the valve is an essential step. Start by first shutting the water supply to the valve off to avoid any further leakage. Next, locate and remove all screws or nuts that are holding the valve in place.

Before proceeding with cleaning or replacing damaged parts, it’s crucial to examine each piece for signs of wear and tear. Be sure to check the O-rings and diaphragms for cracks or any other visible damage.

Remember that proper installation is important when putting back together your backflow preventer. Ensure that every component fits snugly into place and tighten all screws/nuts securely but carefully so as not to damage anything during assembly.

By following these steps for dealing with a leaky backflow preventer, homeowners can have peace of mind knowing their plumbing system is functioning safely without fear of contamination due to faulty valves.

Cleaning and replacing damaged parts

Once you’ve identified that your backflow preventer is leaking, the next step is to disassemble and clean it. Carefully remove the valve from its housing and inspect all the parts for damage or wear and tear.

If any of the parts are damaged beyond repair, replace them with new ones.

Cleaning is an essential aspect of maintenance; use a soft bristle brush to scrub away debris from the surface areas before reassembling everything using Teflon tape on threaded connections if needed.

Finally, turn on your water supply slowly once everything checks out, so that no further leaks occur after cleaning or replacing broken parts.

Reassembling the valve and turning on the water supply

After cleaning and replacing damaged parts, it’s time to put the backflow preventer valve back together. This is a crucial step in ensuring that your plumbing system works correctly and safely.

Make sure to securely tighten all bolts and nuts but avoid over-tightening them, as this can cause damage to the valve. Once you have successfully reassembled the valve, turn on the water supply slowly and check for any leaks or unusual sounds.

Common causes of backflow preventer leaks


Backflow preventer leaks can be caused by various factors, including wear and tear from constant use, improper installation or maintenance, exposure to freezing temperatures, and damage to the valve due to high pressure.

Wear and tear

Over time, regular use can cause a backflow preventer to develop leaks. This is especially true incases where the valve is not properly maintained and serviced. In some cases, seals or gaskets within the valve may become brittle or crack, allowing water to seep through the gaps.

It’s important to be aware of these potential issues so that you can ensure proper maintenance before any major damage occurs. Regularly checking your backflow preventer for signs of wear and tear, like cracks in the casing or rusting around joints will help make sure that it keeps working as it should.

Improper installation

A common reason for a leaky backflow preventer is improper installation. This can ultimately cause issues such as water pressure imbalances and ineffective sealing of the valve, which ultimately causes leakage.

Improper installation can also cause issues with the check valve or pressure relief valve. These valves are critical components of the backflow preventer system and must be installed correctly for them to function effectively.

Freezing temperatures

During the winter months, freezing temperatures can cause a leaky backflow preventer. When the water inside the valve freezes, it expands and puts pressure on the device’s internal parts.

Over time, this expansion can cause hairline cracks or fractures in critical components such as the relief valves or check valves.

To prevent backflow preventer leaks caused by freezing temperatures, homeowners should consider installing an insulated cover over their irrigation system during colder months. This protective barrier will help keep your valve warm and dry throughout periods of frigid weather.


Fixing a leaky backflow preventer may seem daunting, but with the right tools, it can be an easy task. By keeping a keen eye out for leaks and performing regular inspections, you’ll save money in costly repairs down the road while ensuring your safety’s well-being always comes first.

Don’t let leaky valves go unaddressed. They can significantly compromise public health and environmental quality if left unchecked.