Air Conditioning, Heating, & Plumbing

1210 E. Kingsfield Road, Cantonment, FL 32533


CMC1249641 CFC1428103 AL#52965 AL#15167 AL#MPG-4467 AL#M52048

For commercial bids and estimates, email Todd Cooper at [email protected]

How Does a Sewer Backflow Preventer Work?

Occasionally, the city sewer or municipal drainage system overflows and sends waste water back through the sewage pipe and into your home. An overflow can occur for a number of different reasons, including cracks in the pipe, a surcharge caused by large snowmelt or heavy rains, or a blockage caused by tree roots or plumbing system deterioration, and more. However, it can also be caused by a blockage in your home’s own plumbing system due to a failed sump pump, hair clogs, grease clogs, or any other physical obstruction in the pipes.

Fortunately, you can prevent nasty overflow issues by simply adding a sewer backflow preventer to your own plumbing system. So just how does a sewer backflow preventer work? Read on to find out more.

discussing how does a sewer backflow preventer work

How Does a Sewer Backflow Preventer Work?

So just how does a sewer backflow preventer work? Well, it, also known as a sewer backflow valve, stops sewage or water from entering your home through your home’s sewage system in the event that the main sewage line becomes overloaded.

Inside the valve is a small flap that is normally open to permit water to exit your home. It also enables sewer vapors to be released.

There are also small floaters on both sides of the flap that allows the flap to open and close. In the event water or sewage starts to backflow into the house, the floaters will cause the flap to close in order to stop water from entering your home.
Once the water stops flowing in the direction of the house, the flap will naturally fall back into the open position again, allowing water and sewage to continue to flow out of the house.

In most cases, you can check to see if your backflow preventer is properly functioning by peering at the clear-cover backwater preventer access box.

A preventer is typically installed in the main sewer pipe located outside your home; however, it can also be installed in the basement at the farthest point from your home.
There are three main types of sewer backflow preventers: a sewer check valve, an automatic floodgate valve, and a manual sewer gate valve. There also specialized backflow preventers, and each has its own effectiveness.

Types of Sewer Backflow Preventers

Automatic Flood Gate Valve

The Automatic Flood Gate Valve is a fully automatic air pressure device. It is considered the most guaranteed way to prevent wastewater and the hazards and damage associated with it.

The valve contains a stainless steel knife that, once the valve is shut, completely prevents backwater over extended periods of time. Because it is a specialized plumbing device, and because it is larger than the typical backwater preventer, its installation requires expertise. If the preventer is installed improperly, the system may not be as effective. It may also cancel out its warranty.

Sewer Check Valve

A Sewer Check Valve is the least expensive and most common type of backwater preventer. However, since it doesn’t completely stop backwater, it is most commonly used for temporary backups that last no longer than a day.

Once the public overflow diminishes, the check valve will instantly enable your home’s wastewater to exit and run off to the public sewer. However, once the flapper shuts, water use inside the building must be kept to a minimum.
To keep your check valve working efficiently, be sure to have it cleaned at least once annually.

Manual Sewer Gate Valve

A Manual Sewer Valve must be opened and closed by hand. This makes it a great choice for very specific situations. In other words, it is best for those times when you anticipate a backwater situation will arise as well as knowledge of when it will retreat.

Air Gap Backflow Preventer

The Air Gap Backflow Preventer is another simple way to prevent water and sewage backflow into your home.

This type of preventer is simply an open vertical space between any device that connects to a plumbing system. For instance, the clear air space between a water outlet, such as a faucet, and the flood level of a kitchen sink.
In most instances, water is unable to stream from the sink to the tap, even when there is force present in the water supply.

There are no moving parts in the Air Gap Backflow Preventer, except surging water. Many plumbing codes specify minimum air gap distance for many plumbing fixtures.

Specialized Backflow Preventer

A Specialized Backflow Preventer is usually installed near a residential water meter. It is typically installed following the shut off valve.

There are various Specialized Backflow Preventer models available, such as the Pressure Vacuum Breaker (PVB), the Reduced Principle (RP), and the Residential Dual Check Valve (RDC).

Since a Specialized Backflow Preventer can contain moving parts, it needs to be occasionally cleaned and tested for effectiveness. However, when it comes to performing the test and compiling the reports on the drinking water supply, most states only permit licensed plumbers to perform the test.

When installing a Specialized Backflow Preventer, it must also meet the plumbing code. This usually also requires the expertise of a licensed plumber.

The Benefits of a Sewer Backwater Preventer

The main benefit of a backwater preventer is that it stops unwanted backflow from a municipal drainage system or city sewer into your home. This helps prevent health hazards in the environment you reside in as well as the water you drink.

And though the installation and maintenance of a backflow preventer can be complex and require specialized plumbing tools, such as pipe cutters, pipe extractors, a line pressure gauge set up, and brass and plastic adapter sets, there are some preventers that are simple to install.

Without a properly installed sewer backflow preventer, wastewater can enter your home through the sink, tub, floor drain, and toilets.

Wrapping Up

So how does a sewer backflow preventer work? It helps keep your habitat safe from contaminated water flow, which contains funguses, bacteria, parasites, and viruses that can lead to various diseases, infections, and other symptoms.

Once properly installed, your backwater valve can last for a number of years with good care, which includes having it cleaned and checked annually. You should also keep your plumbing system free of unnecessary materials, such as diapers, cigarette butts, and napkins, which will also help extend its function.