What a Backflow Preventer Is, and Why You Need One

November 4, 2021

Backflow preventers aren’t always on the forefront of a property owner’s or facility manager’s mind, but they are an essential component of a plumbing system. Without it, you run the risk of unknowingly contaminating a city’s water supply, which could lead to serious problems for a lot of people.

Here are the answers to some basic FAQs about backflow preventers and why you need one, like “What does a backflow preventer do?”

What is a backflow preventer?

Let’s start off with the basics of backflow prevention: What exactly is a backflow preventer? This is a device that keeps water flowing one way into a property and ensures that no water flows back out into the water system. There are many different types of backflow preventers, but no matter what type you choose, it’s imperative that one is installed on your property.

Why is a backflow preventer necessary?

Backflow preventers help keep water from flowing back into the municipal water supply.

Why is that so important? The answer is simple: It ensures that the water supply does not get contaminated by any non-potable water from an untreated source.

Not all the water in a building is potable. For example, water used in fire-suppression systems is not meant for human consumption. There’s also the possibility that the water has been stagnant for a long time, which can lead to bacteria buildup.

Because it can be impossible to tell what type of microscopic contaminants may or may not be in any untreated water, it must be assumed that any amount of non-potable water that finds its way into a municipal water supply has the potential to contaminate the entire supply.

It’s possible for non-potable water supplies to cross over to a drinking-water line—and if that gets into the main water line for the city, there’s going to be trouble. If the pressure drops in a line, say, due to a water main break or a fire hydrant being opened, it may cause the water in the pipes leading into your property to flow backward. A backflow preventer makes sure that, should this happen, none of that water will go back down the line into the water supply.

How does a backflow preventer work?

A double-check assembly comprises two one-way valves inside the backflow preventer to make sure that water does not flow backward should the pressure drop. In this assembly, when pressure on the property side is greater than the pressure on the municipal water supply side, the valves close up, sealing off the water flow. While one valve would be able to handle this on its own, having two is important for redundancy’s sake to ensure that no water gets past it.

We’ve really only scratched the surface when it comes to what a backflow preventer does and how a backflow preventer works. For more information on this vital part of your plumbing system and for maintenance or installation of a backflow preventer on your property, contact Moody & McClendon Plumbing Inc. today.

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