Why Would a Backflow Preventer Be Leaking?

Why Would a Backflow Preventer Be Leaking

Your backflow preventer is an essential device that prevents the existence of contamination and pollution in your main water source. It does this by simply stopping the fluid from moving backward.

In order to ensure your family’s health and that you are not exposed to any harmful pollutants, it’s important that your backflow preventer is in proper working condition. However, one of the most common issues with the device is leaks.

The reason why your backflow preventer might be leaking can be due to a number of issues and the leaks often occur at the connection point of the valve body and cover. Whether its failure due to wear, pressure that’s too high, incorrect placement or debris; your leaking issue should be fixed.

We’ll explore all of the possible causes for your leaking backflow preventer as well as some tips on how to troubleshoot the issue.

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What Is A Backflow Preventer?

A backflow preventer is essentially a device installed on your home’s water pipes that allows water to flow in one direction but prevents it from flowing in the opposite direction. The sole purpose of this device is to prevent backflow from occurring, ultimately contaminating your drinking water.

It’s best explained as a one-way street for water. Backflow preventers will keep any unsafe water from reversing its flow and polluting the clean water supply. Your backflow preventer may be as simple as a single valve closing when water reverses or as complex as a system of multiple check valves, water release valves and air vents.

The backflow preventer is most often installed between the sprinkler or irrigation system in your home and the water supply connection.

What Causes Backflow to Occur?

As water enters into your home from the main water supply line, it should always flow in one in only one direction. However, in some cases, pressure changes in your pipes can cause the water to flow in the reverse direction and back into the main water supply.

For instance, if there is a break in the main water line or a fire hydrant is in use, backflow may occur. This typically happens due to pressure loss and since water is no longer being pushed forward into your home it will instead flow backwards.

As previously mentioned, when backflow occurs it has the potential of contaminating your water supply and the public drinking supply. Some of these harmful pollutants include:

  • Human waste
  • Pesticides and fertilizers
  • Chlorine or other chemicals from pools/spas
  • Soap from showers/sinks/dishwashers
  • Other garden chemicals or debris

This is why a backflow prevention system is an essential tool to preventing any sort of contamination.

Why Is My Backflow Preventer Leaking?

It’s not only important to have a backflow preventer but also to have one that is functioning properly. If you notice that your device is leaking, the first thing you should check is the washer seal in the female connection. This is a rubber washer than can dry out or deteriorate over time. It should be checked and replaced often to prevent leaking.

However, if this is not the problem, you may be experiencing one or a combination of the following issues:

High Pressure – In the case of your irrigation system, the backflow preventer functions by maintaining a lower water pressure in relation to the domestic water source. If the pressure in your irrigation system is too high, this will cause a relief valve to open. The valve will remain open, displacing and discharging water until the correct pressure is restored.

Debris – If the issue you are experiencing is a constant slow leak, this is most commonly caused by debris in the system. Debris such as sand or dirt can enter the seat of the relief valve from the domestic water source. This will prevent the relief valve from closing completely.

This issue is very often a reoccurring problem and requires many service calls to a local plumber to maintain the system. Installing a filter prior to the backflow preventer on the domestic water source can stop debris from entering into the relief valve.

Improper placement in the head assembly – This is another common cause of backflow preventer leakage. If the preventer is located upstream from a timer and the hose is on but the system is not being used, the pressure will build; damaging the backflow preventer. To relieve this pressure, water will leak out from the relief holes.

If a timer is used, it should be installed prior to the backflow preventer. These parts should only be hand tightened and if they’re over tightened, the washer seal can become damaged. This will result in cracks that will also cause leaking.

How to Troubleshoot Your Leaking Backflow Preventer

It’s important to understand that this device is not immune to leaking and it will occur from time to time. If your system is leaking, we recommend calling a professional plumber to fix the problem.

However, if you’ve discovered that some faulty components inside your backflow preventer are causing leaking, here are the steps that you can take to dissemble the device and troubleshoot the issue yourself

  1. First, shut all the valves to the backflow preventer.
  2. To isolate the backflow preventer, you’ll need to relieve some pressure. The plugs on the side can be removed and allow water to drain out.
  3. Take off the nut on top of the bell to completely remove it. Be careful not to strip it as it will need to be put back on when reassembled.
  4. At this point, slowly open the valve and notice how the water will start to fill up, overflow and pop up with the existence of more pressure.
  5. If you’re still experiencing leaking out of the side, this suggests that something is blocking the gasket or it’s damaged.
  6. Remove the poppet and bonnet by hand or by using a wrench and inspect the interior of the device.

Now that you’ve dissembled the backflow preventer whether it’s a broken gasket or other faulty component, you should have visibility to what exactly is causing the leaking problem.

Other Signs That You Need a Backflow Preventer Repair

Aside from the obvious leaking from your backflow preventer, there are other signs that the device may need repair. If your water is contaminated, it may appear as follows:

  • Water flow may be interrupted or slow moving.
  • It can be discolored, appearing either brown, yellow or even pink.
  • The water has a bad Sulphur odor.
  • Bad tasting water.
  • The presence of visible sediment or rust particles in the water.
  • Drains draining slowly.
  • Simultaneously having increased water level in some drains and decreased water level in others.
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Common Problems That Cause A Backflow Preventer to Fail

It’s important to have an experienced professional look at and test your backflow preventer for any signs of problems within the assembly. If left unchecked, the issues can impede the device’s ability to function and be potentially disastrous in the event of a nearby burst water main.

Here are some common problems that cause a backflow preventer to completely fail:

Relief valve opening point too high – In terms of PSI, different backflow preventers will be designed with varying minimum thresholds. If the relief valve disc isn’t embedding itself correctly, the opening point can become too high.

Relief valve opening point too low – This typically happens from something restricting movement into the relief valve stem mechanism.

Faulty first check valve – In a reduced pressure backflow preventer, the first check valve will open at particular water pressures. Typically, when the water pressure hits a minimum of 2.0 PSI, the valve will open. If it is faulty, it may open at lower pressures and impair the performance of the overall device.

Faulty second check valve – Testing a second check valve involves looking for signs of backpressure. If the valve has failed, water can leak past it and back into the area between the two check valves.

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Jessica Stone

Jessica considers herself a home improvement and design enthusiast. She grew up surrounded by constant home improvement projects and owes most of what she knows to helping her dad renovate her childhood home. Being a Los Angeles resident, Jessica spends a lot of her time looking for her next DIY project and sharing her love for home design.

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