How to Install a Backflow Preventer

A backflow preventer is designed for use with irrigation systems and water pipes, preventing water from flowing back up the pipe as you might guess. Most backflow preventers are mechanical devices which create a physical barrier to accomplish this.

If you wish to install your own, you must make sure that your mechanism is compatible with the water source you will be using, and that you feel confident about being able to install this complicated piece of machinery yourself, without assistance. If you are fairly sure that you can replace the system, then you should follow these simple rules in order to press ahead with your installation.

Step 1 - Get Ready

Before you begin, the most important thing that you should do is check the building code in your area. If you have any doubt, the local building code office, or your water supplier, will be able to tell you how deep you need to install your pipe, the dimensions allowed for the backflow preventer box, and the limits of installation. You should always check what is allowed in your neighborhood before commencing so you do not waste money on a project that won't last. Conditions like low winter temperatures, for example, can affect how deep you need to dig.

Step 2 - Locate the Pipe

Once you are sure that your machine will not break the building code, then you can proceed. Dig down by the water main which is connected below your curb. You will find a one-inch copper pipe, which can be split into smaller pipes at the meter box. Everything which is on your home's side of the meter belongs to you. Close by the meter will be a valve used to shut off the water during repairs in the home. There may also be a pressure reducing valve nearby, as well as small dimples near the valves known as meter nipples. You may have to dig up three to five feet away from the meter before you are clear of all this.

Step 3 - Install the Backflow Preventer

There are two different types of backflow preventers you can use. The first is called the Threaded and Glued, and it involves dropping a threaded T-device into the pipe to connect it to the pressure valve adapter. Occasionally, this version requires that there be extra length in the line, so a small section will have to be removed so that a joint can be added.

The other version involves a compression fitting, which relies upon a pressure washer to seal around the outside of the supply pipe. Cut a small piece of the line, and the install a compression fitting around the cut. This will tighten and prevent water from flowing backwards. Find a metal compression device with a rubber washer fitting, and make sure to tighten it properly, without cracking the pipe or damaging the compression valve.

With this, your backflow preventer will be successfully secured in place for immediate use.

Backflow Preventer FAQ

Where is the best place to put a backflow preventer?

While backflow preventers are installed in a number of places, including inside buildings and underground, the best placement is above the ground and outside the building. The backflow preventer should also have an enclosure.

What is the difference between backwater valve and backflow preventer?

Blackflow preventers are used to keep drainage water from residences and buildings from being released into the municipal water supply. The pipes and drains that connect to the municipal water supply don't dump dirty water into clean water thanks to backflow preventers.

Backwater valves prevent dirty water and wastewater from getting into your home. Once the drainage water exits your home, the backwater valve keeps that water from backing up into your pipes.

What devices need a backflow preventer?

Backflow preventer requirements vary by local plumbing codes. But on the whole, all water outlets should be equipped with a backflow preventer to prevent water contamination.

How high should a backflow be off the ground?

A backflow preventer should be at least 12 inches off the ground, one foot, but no higher than four feet above the ground or floor.

The backflow preventer needs some airflow and some empty space underneath it. This is in case the backflow preventer fills up and water pools up underneath it.

However, height requirements for backflow preventers can vary based on city, county, and state laws. Check with your local office of plumbing permits to find out what the requirements are in your area.

Does a backflow preventer increase water pressure?

If anything, you will notice a small drop in water pressure after you install a backflow preventer, rather than a rise. You should not notice a significant change in water pressure either way, however, so any change in water pressure indicates a problem.