If you have a backwater device, it may be in the form of a standard plug and is usually located near your main shutoff for the house.
A backwater valve is a device installed in the drain line of fixtures that are susceptible to flooding, i.e. toilets, sinks, etc., that prevents water from the sewer or public system from entering the home when there is a blockage upstream. When used in sewer backup systems, the backwater valve is also referred to as the backflow valve or the sewer backup valve.
When one or more fixtures are flushed simultaneously, water can flow through each fixture at different rates. This results in unequal pressure in the piping system and may cause siphoning of water out of traps in susceptible fixtures. That circumstance creates the potential for sewage gases to be drawn inside the home—a condition known as "backflow". Siphonage also increases the risk of dirty water backing up into an unflushed toilet bowl or overflowed sink - which not only poses health hazards but creates water damage.
The most commonly used backwater valve is the swing check valve. The swing valve uses a hinged flap that maintains a watertight seal until enough wastewater builds up to allow for the opening of the valve. When wastewater levels subside, an internal spring mechanism closes the valve again, making it capable of withstanding positive pressure from below as well as negative pressure above, which makes this type of backwater valve more effective than gravity-operated devices. Most standard residential installations have one or two valves controlling all drain lines running between fixtures and either main sewer line or septic tank respectively.If you have a backwater device, it may be in the form of a standard plug and is usually located near your main shutoff for the house. If you remove this plug, water will not come out. Its purpose is to prevent unwanted water from entering your home when there is an issue with the city sewer mainline, during heavy rainfalls, or during maintenance of the municipal sewer system, such as rodding the lines. There may also be a backwater valve in the basement below the floor drain. This is not normally the preferred location but could be necessary for some applications when there is no other alternative. The best way to determine if you have a backwater device at your home or business is to contact a qualified plumber and ask them to check for this item. They'll also assess if you need a backwater valve and will install one if you don't have one installed already.
A backwater device is installed inside the sewer lateral between your sewer line and your home or building. It stops water from backing up into your foundation, basements, crawlspace, first floor or other areas where it's not wanted. As wastewater flows through the main sewer line toward the treatment plant, it creates pressure called head-pressure. The patented design of a backwater valve opens during periods of heavy flow so that there is no risk of backup but closes during lighter use giving you complete protection against nuisance backups without wasting precious water.
There are several types of backwater valves on the market. Some of the most common types include:
This type is installed in solid walls and has a disc that rotates either by its own weight or by water flow pushing against it to seal against a rubber gasket. It moves through a sleeve called an actuator which allows for adjustment of the valve's size and provides pressure relief during periods of low use.
This type comes as two half circles with flat faces and is directed by gravity using steel balls on top to rotate and open during periods of high use, then swing back over to close off the flow when usage decreases.
This unit is installed in a pipe and uses a lift to open during periods of high flow. It is lifted by the wastewater flow and falls back due to gravity when it's not needed.
This type is also installed in a pipe but works by expanding and contracting like an accordion as water flows through it. It's operated the same way, using a lift on top so that wastewater can move unrestricted at all times.
If the valve needs cleaning to get it working properly, you should contact a licensed plumber to do proper maintenance for you. They'll know what chemicals to use and the sequence in which to clean them so that they are not damaged or corroded by certain types of cleaners or harsh chemicals.
It's best to schedule installing backwater valves when any major work is done and not try and squeeze it in yourself between projects. Most communities have by-laws requiring the installation of a backwater valve on all properties connected to either a sanitary sewer line, combined sewers system, or city sewer lines.
Your home insurance provider may require you to have a backwater valve installed in the sewer system before insuring the property. Installing a backwater valve is a requirement in the prevailing plumbing code. You may also need to confirm with your agent if you are considering taking home insurance.
In practice, the backwater valves are installed on the basement floor. The plumber will make a hole on the concrete floor near the floor drains to access the plumbing system. Most installations require the plumber to disconnect downspouts to reach the foundation drains properly.
Mostly, they will be located close to the sump pump. If you want to check if the backwater valve is functioning properly or wish to perform regular maintenance, look out for a rectangular panel in a clear compartment. Open the panel to access the round cap for cleaning and check if the valve is working correctly. Ensure you are wearing gloves and protective eyewear when performing regular maintenance of the sewage water plumbing system.
On average, a backwater valve costs about $1500 to $3000 install and that covers the cost of parts, labour, equipment rental, and transportation costs. The work involves several specialised trades like pipe-layers, pre-approved plumbers, and sometimes electricians.
A backwater valve can help reduce or even eliminate the below.
Sewage odours and leaks around the foundation.
Backups caused by heavy rain.
Leaks due to tree roots invading sewer lines.
Blockages caused by grease build-up in main drains.
Raw sewage backups into your home, basement or crawlspace.
Overflowing toilets during peak periods.
Clogged drain pipes plugged with soap scum/hair/debris.
Nasty water discharge from laundry drains.
Smells coming up through shower drains.
Broken or damaged drain tiles allowing waste to seep into the surrounding soil.
Typically check valves can be made up of rubber or plastics, whereas backwater devices are metal and very durable. Check valves tend to wear out more quickly than backwater units since they're pushed open by the flow but must also close completely even during periods of low use.