Adapt-a-Valve Extendable Backwater Valve

The Adapt-a-Valve Extendable Backwater Valve was invented because there was a need to have easy access to enable servicing  of backwater valves deeper than 2 feet.  The only other options were expensive and unsightly ‘vaults’ or ‘access culverts’ in which someone had to crawl down to service the backwater valve. Another option, which was strictly against code but done by unscrupulous persons, was to completely bury a valve with no intention of ever servicing the backwater valve. The Adapt-a-Valve not only made extendible backwater valves easy to install, inspect and service, but with the special gate slot molded right into the body, it could easily be used for ‘pressure’ testing the ground works by adding the Test Gate feature. Hence, the name Adapt-a-Valve – because it could be adapted to various functions!


Available in ABS and PVC

The combination Mainline “Adapt-a-Valve” Backwater valve is a break through in technology and is quickly setting a New Standard across North America.

Physical Properties

The Adapt-a-Valve comes in two sizes; 3” with a 4” riser and 4” with a 6” riser.

The Adapt-a-Valve has integrally molded guide slots in the body which allow the fitting to be converted at any time to a backwater valve or a pressure testing device by simply adding from the list of the accessories available, should the need arise!



“Adapt-a-Valve” backflow accessories are what excel this extendible backwater valve years ahead of its time. The

“Test-Eze” gate for the Isolation of the sewer system

“Normally-closed” cassette (swing check)

“Normally-open” cassette which maintains the free circulation air from the plumbing system to the city sewer system.(available on 4” model only)

These optional accessories give the fitting the versatility that no other fitting has! (Details Yellow Brochure)

Design / Engineering


In the engineering of the Mainline “Adapt-a-Valve”  reliability was placed at the forefront.

We know that backwater valves are mechanical devices and require maintenance/cleaning to work effectively. They are products which are generally never maintained and are out of site - out of mind therefore the failure rate is high because they are only maintained or serviced after failure.

Because they sit in a sewage environment with little or no maintenance, Mainline’s engineering staff knew that they needed to design a fitting that promoted “self cleaning”.

The “self cleaning” – type action was achieved 3-ways!

The offset “step through design” from inlet to outlet gives the valve the grade that  no other valve has, ensuring that no solids will build up in the valve body.(3/4” offset for 3” and 1 ¾” for the 4”)

Using the valve in the “Normally- open” configuration allows this grade to continue through the body and offers zero flow restriction.

Utilizing the valve with the “Normally-closed” Cassette / Gate (swing check) we used a light weight gate with a lubricous shinny face that would not collect with sewage and restrict the flow.

In studying industry standard backwater valves (swing check) we found three common design flaws with every valve on the market:

#1. Every manufacturer has the seal on the gate, whether through the use of an o-ring or the use of a solid rubber gate. The problem with this is that because sewage has to push this gate open sewage easily collects and adheres to the o-ring or rubber gate.

#2. Some manufacturers use a heavy gate design with rubber gates and have a ‘living’ hinge for the swinging motion. This heavy gate can cause flow restriction and can attribute to solids building up on the gate making them ineffective during sewer back-up occurrences. 

#3. All manufactures have minimal drops ¼” through the valve bodies with little or no grade built through the body.

The result of these three design flaws means that sewage hits a heavy gate and slows right down, sewage collects on gate sealing surface and sewage stops with the minimal grade through the body. Stopped or slowed sewage will rest and settle at the bottom of the valve. All three of these flaws are common denominators to a high maintenance valve.

In the designing of “Adapt-a-Valve’s” “Normally-closed” Cassette / Gate (swing check) the approach was simple: avoid the three contributing factors to valve failure. Because “Adapt-a-Valve” uses a cassette style cartridge, the seal is on the cassette not on the gate. The gate has a shiny lubricous face where sewage does not collect.  “Adapt-a-Valve” utilizes a gate so light that one can literally ‘blow’ it open. Result? Next to no flow restriction.  “Adapt-a-Valve” has a 1¾ ” drop through the body on the 4” valve and ¾” drop on the 3” valve which means ample grade through the body. This ensures that no sewage will remain in the valve body. 

The advantage is that you have the very best in valve design when maintenance is of a concern. The step through design does limit “Adapt-a-Valve” to new construction and retrofits are allowed only when replacing the entire line to make up the inlet to outlet differences.

Test-Eze Gate (Isolation Valve and Pressure Testing)

The insertion of the Test-Eze Gate allows the system to be pressure tested as well as ‘isolation’ of the lateral . Isolation gates are used for closing off of the sewer system for flushing of city mains, servicing of sewer lines, abandonment of premises, disconnection due to non-payment of utilities, isolation of seasonal properties / hurricanes / etc., diversion valves for septic fields and for contractors pressure testing of plumbing systems upstream of the Inspection chamber / cleanout. A very versatile accessory!

Extendable Feature “EASY ACCESS”

Because backwater valves are mechanical devices and require access for maintenance, plumbing codes state any backwater valve deeper than 24” requires them to be installed in vaults or manholes. The “Adapt-a-Valve’s” ‘extendable features’ allow the body to be extended with standard DWV pipe and the cassette to be extended with standard ¾” PVC pipe. By extending the body and cassette the backwater valve feature can easily be removed or inserted from the top of the valve body opening this allows for easy servicing at any depth, eliminating the need for expensive vaults or manholes.             


By installing the “Adapt-a-Valve”  Backwater Valve municipalities North America wide will have at their disposal the very best in technology.  A municipality would have a “quick fix” solution with “Adapt-a-Valve’s” exceptional backflow protection options should a municipality ever experience a problem with sewer backups in any lateral. These backflow options would protect the lateral from backup thus saving the building from thousands of dollars in damage that could result in potential claims against the municipality.

Diagrams ( ML-4XA/P Adapt-a-Valve)

Adapt-a-Valve Diagram