How Does a Backflow Preventer Work in 2021?

What is a backflow preventer exactly? Do you need one in your home? And for the especially curious, how does a backflow preventer work? As certified backflow preventers, we have the answers for you here at Plumbing One.

Clean water is a pretty necessary part of domestic life. After all, where would we be without the ability to brush our teeth, wash our dishes, or fill a glass at the sink after a sweaty afternoon working in the yard? A backflow preventer is one of the crucial parts of a water distribution system that makes these things possible.

Let’s take a look.


Also known as a backflow device, a backflow preventer is a plumbing valve that a plumber can install on your home’s water pipes. The purpose of installing this valve is to keep your water supply safe from contamination.

Water comes into your home from your main water supply. As you might imagine, the ideal scenario is to have that water flowing in, yes, but never out of your house. Unfortunately, when pressure changes in your pipes, it’s possible to get backflow. This is where water will actually flow the wrong way (i.e. back into your main water supply). This is dangerous because that water — we’re talking about drinking water here — may now be contaminated with toxic substances like fertilizers, pesticides, and human waste.

Your backflow prevention system will accomplish a job very similar to that of a standard hose bib vacuum breaker on your outdoor spigot, according to AskingLot. Both devices exist to prevent similar backflow scenarios.


Your backflow device is positioned on your water pipes and designed to regulate flow directionality. Though small and assuming, these devices are actually pretty sophisticated. A backflow preventer can execute quite a few different maneuvers, depending on the scenario. As the following video illustrates, a series of chambers work together inside the device to ensure that whenever there is backflow, that contaminated water is isolated in a chamber, properly released, and ultimately kept away from your main water supply line.



As I mentioned, Plumbing One technicians are Certified Backflow Testers. A certified backflow tester is someone who has undergone the training that allows them to install and assess the functionality of backflow devices. Point being, testing for backflow is not a good DIY project. Similarly to a sewer line repair or a particularly involved garbage disposal replacement, it’s probably better to call the pros when you need to work on or install a backflow device.


We can certainly take care of that for you. The City of Columbus mandates that where backflow prevention is required, the valves must also be tested once per year. However, this is a good rule to follow even if the device isn’t mandated in your situation. As you’ve hopefully learned, a leak or failure with these valves can result in some pretty unsavory chemicals and toxins seeping into the water you use every day. 🚰 😳 🌊

Give Plumbing One a ring with any backflow prevention questions today!

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A plumber working on the pipes on the underside of a bathroom sink.

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Plumbing One is a family owned and operated plumbing company. Our A+ rating from the Better Business Bureau demonstrates the level of quality and integrity we bring to every job site. Regardless of how big or small your residential or commercial plumbing job may be, your satisfaction is 100% guaranteed. Call us or fill out the online form to get in touch with a plumber from our team.

A plumber working on the pipes on the underside of a bathroom sink.