How to choose which Backwater Valve I need?
Why a Mainline Valve
How it Works
Mainline Backflow Products
Canadian Home Builders' Association
Mechanical Contractors Association of Alberta
If you have a basement the most popular backwater valve used is the "Mainline Fullport Backwater Valve". This valve is typically installed on the Main-Sewer line entering the building and protects the entire building from backflow; it comes only in a 4-inch DWV size, ABS or PVC. The valve has clear lid for ease of maintenance and incorporates a built-in Main-Sewer cleanout. This valve is used to protect half the homes using backwater valves in Canada and in certain US States. CSA and UPC certified
On-Slab Applications or deep burials
The Extendable "Adapt-a-Valve" backwater valve is ideal for exterior installations, deep burials and commercial applications. This valve simplifies backwater valve installation, on standard backwater valves you typically need expensive vaults and access boxes which are heavy and do not provide adequate access to service valves buried deeper than 24-inches. With the Extendable "Adapt-a-Valve" you eliminate the need for expensive vaults and access boxes and saves labor. The extendable valve body feature makes servicing of the valve easy at any depth. The valve comes in both 3 and 4-inch sizes, DWV and both in ABS and PVC. Popular choice for on-slab buildings with exterior installations, commercial CSA and UPC certified
Retrofitting Valves in existing Systems
Before selecting the valve you use, you must know the limitations of all backwater valves. Every valve on the market has a step down design, meaning the outlet is lower than the inlet. This difference in elevation may result in back grading of the valve which in turn dictates the amount of maintenance a valve requires. Check with your Contractor which valves works best for you!
"Mainline Fullport Backwater Valve" is the most popular retrofit valve we manufacture the elevation difference is æ" between inlet and outlet. Installation into retrofit systems has been successful one with this valve with approximately 4,000 valves installed. Generally the æ" difference is made up by the contractor by slightly raising 3-4 ft. of piping leading up to the valve on the inlet side. Depending on your piping grade determines whether or not you need to raise the piping leading up to the valve.
"Adapt-a-Valve" This valve is difficult to retrofit into a system if you are not replacing the sewer lateral. The 3-inch "Adapt-a-Valve" has a 1-inch difference between inlet and outlet and the 4-inch "Adapt-a-Valve" has a 1æ-inch difference between inlet and outlet.
Generally this valve cannot be used in a retrofit system unless #1 You are replacing the entire line (lateral) outside the building where you can make up the height differences or: #2 You are installing it at the property line where you can generally make up the difference where it ties into the city sewer.
So Choose Carefully!
For more information contact
Mainline at 1-877-734-8691