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Backwater Valve

Backwater Valve Information

The Arkansas Plumbing Code and City Ordinance 92-019 require you to have a backwater valve if your plumbing fixtures are below the top of the first upstream manhole on your street. It is always good to have a backwater valve installed even if you do not meet the criteria listed above. A properly operating backwater valve allows the flow to only go in one direction, thus preventing wastewater from entering your building during regular sewer system maintenance or an inadvertent sewer system backup.

Backwater Valve diagram

To find out if you have or need a backwater valve, check your plumbing plans or consult with your builder or professional plumber. If sewage backs up into your home, the cost to repair damages and clean up the mess may be costly, and the City of Mountain Home cannot be held liable for damages. Below are pictures of what a backwater valve looks like and how they might be installed.

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Backflow valve
Backflow valve details

Getting to know backwater valves (Information)

Whenever there's a sudden downpour or a blockage in a sewer main, there's a risk that your basement or main house could experience a sewer backup problem. It's bad enough if clean rainwater backs up in your basement, but try to imagine dirty sewage filling your basement or your home, ruining everything it touches. Fortunately, you can help prevent this by installing a backwater valve.

What is a backwater valve?

A backwater valve (sometimes called a backflow or sewer backup valve) is a valve you can install on your sewer line and is designed to allow water or sewage to flow only one way, that is, out of your house. Anytime there is a sudden heavy rainfall, the city sewer lines can become overwhelmed, causing water or sewage to flow back towards your home. If there is a sewer system backup, and you have a backwater valve in place, sewage will not be able to flow back into your house.

The risk of sewer backup increases if there is a basement in your home, or if the ground floor is less than a foot above street level. If a new home has any fixtures located lower than the street level, it is a requirement of The National Plumbing Code to have a backwater valve installed.  It is always recommended that a backwater valve be installed even if your dwelling does not require one; there are so many instances that can cause backups in a home and City's cannot be held liable for any damages.  

Backwater valves are required by some municipalities and recommended by others.  They can be installed in the initial new construction or can be retrofitted into existing homes.  Contact a licensed plumber for cost estimates for install.

How does it work?

Your home's sewer system allows water and sewage to flow out of the house. A backwater valve will stop water or sewage from flowing into your house should the main sewer line become overloaded. In most cases, you can check to see if it's working properly by looking through the clear cover on the backwater valve access box.

Inside the valve is a small flap that is normally open allowing water to exit your home. It also allows any sewer gases to be vented. There is a small floatation device on each side of the flap. If water or sewage starts to flow back into the house, these floaters cause the flap to lift up and close, thus preventing anything from entering your home.

When the water stops coming back towards the house, gravity will allow the flap to fall into the open position again, allowing water and sewage to resume flowing out of the house.

If this backwater valve is being put in an existing home, as opposed to being installed in the initial construction, a plumbing permit from your municipality is needed. A licensed, qualified plumber will have to cut a hole in the concrete floor, usually near the floor drain. They will dig down to the main sewer line, cut out a portion, and replace it with the new valve. These valves often have a clear top so you can see if it is operating properly. There is a lid that can be removed for cleaning.

Without a properly placed and installed backwater valve, sewage could come into the basement or main house through a floor drain, sinks, tubs, and toilets.

  •     Talk to your municipal government to find out if any local permits are required, as well as to find out what sort of equipment they recommend.
  •     Check that your foundation drains & rain downspouts are not connected sanitary sewer. These are not to be plumbed to the sewers.  In most cases, if you disconnect the foundation drain, your home will require the installation of a sump pit and pump. It is recommended to talk to a plumber and your local government department for advice on how to properly disconnect downspouts and foundation drains.
  •      Hire a licensed plumber. They can install the backwater valve and can also obtain any necessary building permits.
  •      Make sure foundation drains & rain downspouts, once disconnected from the sewer system, drain away from your home and to the street where storm drainage is to be placed, but not directly toward your neighbor's property.

What should you do when something goes wrong?

If you have a properly positioned and installed backwater valve, you shouldn't experience much in the way of problems, as long as you have been maintaining it properly. Things can get stuck, preventing the valve from closing, or the valve can get damaged by sharp items. Proper, regular maintenance can catch these issues before there is a serious problem. Backwater valves are usually easily accessible, and with a clear top, you should be able to see if water is flowing freely or if anything is stuck. There are a wealth of instructional videos to help you "do it yourself," or you can call an expert if the thought of sticking your hand in a sewage pipe is not particularly appealing. If you do attempt to clear a block on your own, be sure to follow ALL the instructions carefully, especially wearing gloves.

If everything is clear, and the city sewer backs up during a major rainstorm, your backwater valve will close, which is exactly what you want to happen. But when that valve is closed, water cannot flow out of your house either. There is a certain amount of storage space in your plumbing system to account for this, but you may not want to shower and run your washing machine or dishwasher all at once during a major rain storm, or an extreme period of melting snow. Since none of this water will be able to escape once the backwater valve is closed, you could wind up flooding your own house.

What can you do to maintain your backwater valve?

You should check at least annually to remove any debris that could clog the valve and to make sure all moving parts have free movement. Most valves have an easily removed cover, to allow quick cleaning. But be careful. Some experts recommend running some hot soapy water down your sink first to make sure the system is fairly clean. Always wear rubber gloves and use a long handled brush to scrub around and under the flap. Most backwater valves will have manufacturer's recommendations regarding maintenance.

You'll also want to look at the O-ring around the lid to make sure it's in good condition. If not, it should be replaced to ensure a proper seal. Also, check the floats at each side of the flap, and replace if necessary. If these are worn, they will lose their ability to float, and won't be able to lift the flap when needed.

To keep everything flowing smoothly, you may want to consider NOT flushing such things as "flushable wipes" or diaper liners. By disposing of these things in the garbage, rather than in the toilet, you will be saving your system from performing extra work, and will hopefully be preventing the system from getting clogged.

If you're unsure about the condition of the valve, or are not comfortable attempting it yourself, you can call a plumber to do an inspection.

What is the life expectancy?

Your backwater valve should last many years with the proper maintenance. Follow the manufacturer's recommendations, and at a minimum, have the valve checked and cleaned once a year. And as mentioned above, keeping your system free of unnecessary materials, will also help to extend the life expectancy.

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