Plumbing problems can be quite a hassle to deal with, especially if these problems rise from blocked drains. If the main sewage line connected to your home gets blocked, the backed-up sewage finds a way out through the lowest drain available. 

In most cases, this is the floor drain located in the basement. However, installing a simple plumbing device can ensure you do not come home to a sewage-flooded basement. And the best part is that you could install that device yourself. 

The device is called a backwater valve, and this short read will tell you everything you need to know about it.

What is a backwater valve?

backwater valve

The way drains are designed is that sewage flows downhill into the sanitary sewer. A backwater valve, when attached to a floor drain, has a one-way gate that opens up every time sewage goes down the drain.

However, when your sewer line gets blocked or clogged, that sewage backs up towards the floor drain and pushes against that gate in the opposite direction. This automatically shuts the gate, preventing the sewage from entering your home.

People often mistake backwater valves for backflow preventers. However, the two devices differ in their primary function.

Backwater valves are attached to floor drains to prevent backed-up sewage from entering your home. Backflow preventers are attached to water supply pipes, and their purpose is to ensure water flows only in one direction, towards your home. They prevent water from getting contaminated and re-entering the main water supply, thereby reducing the risk of contaminating the water supply.

Is a backwater valve necessary?

backwater sewer line

A backwater valve is necessary, and in most places, is a part of the code. So before you run off to the hardware store to buy one, it may be a good idea to remove your floor drain cover and check if there already is one in place.

If you notice there isn’t one in place, you may want to check with the authorities in your city building inspection department. It may simply be that it is very unlikely that your neighborhood is going to experience sewage backups. 

In any case, installing a backwater valve is a fairly easy process that you could do yourself. While a professional installation by a certified plumber could cost anywhere between the national average of $300 to a high of $1,000 including labor, the part in itself should not cost you more than $100. The entire process should not take you more than fifteen minutes. 

You ought to be able to buy a backwater valve online, at hardware stores, or at plumbing supply stores.

What you’ll need

How much should I save for maintenance on my home

In addition to a backwater valve, you will need the following tools.

  1. A screwdriver
  2. Locking pliers
  3. A wire brush or old toothbrush
  4. Pipe thread sealant for use on plastics

The process

  1. Unscrew the basement floor drain cover and clean the thread on it with a wire brush or old toothbrush.
  2. The valve has two parts: a ball and an insert. Apply the pipe thread sealant on the threads of the valve insert.
  3. The ball must be dripped into the sewer and the inlet must be screwed into place. The easy way to do this is to use a rubber bush at least 2 inches wide. After this, hold it with the pliers to screw the insert in place.
  4. The ball remains floating in the sewer until such a time that the sewage levels rise. Then, the ball rises towards the insert and seals tightly against it, effectively preventing sewage from entering your home. 
What is a backwater valve floor drain and do you need one? was last modified: July 22nd, 2022 by Narayan Shrouthy
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