top check backwater valves backwater check valves backwater valves adapt-a-valve information ml fr4 fio valve information termex valve information straight fit backwater valves backwater valve diagram backwater valve features and specifications backwater valve history testimonials backflow prevention information helpful links backwater valve pricing frequently asked questions backwater valve specifications backwater valve installation tips backwater valve animation backwater valve videos contact us backwater valves main page backwater valves backflow prevention links


Backwater Valves backwater valve pricing

Recommended Brand: Mainline Fullport Backwater Valves
-  Models # 4963 A (ABS) and Model # 4963 P (PVC) and the NEW Top Check Valve # PVC4TC (PVC)

new mainline topcheck valve operation

As unsettled weather patterns continue to drop unprecedented amounts of precipitation on widespread regions of the United States, officials urge homeowners to consider installing backflow valves.

According to the Department of Homeland Security’s Federal Emergency Management Agency (FEMA)*, flooding can sometimes cause sewage from sanitary sewer lines to back up into houses through drainpipes. These backups not only cause damage that is difficult and costly to repair, but they also create health hazards.

A good way to protect against sewage backups is to install backflow valves, which are designed to block flow into the house.

backwater valve backflow valve placementValves vary in complexity, tightness of their seals and ease of operation.  For example, gate valves are  generally complex and require you to be there at the time of crisis to operate them by hand, but they supply a very tight seal.  Flap or check valves, which allow flow out of the house and close automatically when flow reverses, are simpler.  backflow valve backwater valveOur award-winning Mainline check-valve design offers an exceptionally tight seal when compared to a gate valve and still requires periodic testing, but they protect you automatically, even if you are not at home!

top check backwater valve purchaseMany municipal Building Codes require you to have a backwater valve if your plumbing fixtures are below the top of the first upstream manhole on your street.  A properly operating backwater valve allows flow to only go in one direction (out), preventing wastewater from entering your building during regular sewer system maintenance or accidental sewer system backups.  To find out if you have or need a backwater valve, check your plumbing plans or consult with your builder or a professional plumber.  Remember, if sewage backs up into your home, the cost to repair damages and clean up the mess will be well higher than the cost to install a valve.  Laws allow that towns and municipalities cannot be held liable for damages when a backwater valve has not been installed by a property owner.  Truly, "an ounce of prevention is worth a pound of cure!" 

The following should be kept in mind when installing backflow valves:

.  Local codes and ordinances regarding backflow valves must be carefully checked to avoid having to tear out and replace with an approved valve.

. Changes to home plumbing must be done by licensed plumbers or contractors, who will ensure that the work is done correctly and according to all applicable codes.  Costs are likely to range from a few to several hundred dollars.

. Some valves incorporate the advantages of both gate and flap valves into a single design.  Plumbers and contractors can provide advice on the relative advantages and disadvantages of the various types of backflow valves.

. Valves should be installed on all pipes that leave the house or that are connected to equipment that is below the potential flood level.  So valves may be needed on washing machine drain lines, laundry sinks, fuel oil lines, rain downspouts, and sump pumps, as well as sewer/septic connections.

. Sump pumps are sometimes connected to underground drain lines, which may be difficult to seal off.

Access Box PE 2013ACCESS BOX NOTES: The Access Box is intended to be used as an access opening for the Mainline Fullport Backwater Valve Model # 4963 and may be used for other access applications (example: cleanouts, irrigation etc.).  The overall width of the open base of the black PE 2013 Access Box is 14-7/8" X 20" and steps down to 11-1/8" X 14-7/8" at the top of its 16" height. The removable gray high density polyethylene (plastic) top access panel is 10-7/8" X 14-1/2". The access box top is held in place by two 1/4" Plastic Push Fasteners.

IMPORTANT NOTE: Pipe end-to-end, the Backwater Valve takes up 12" of run in your line.  The outlet is 3/4" LOWER than the inlet, so in 12", the level of the pipe at the outlet side now needs to be 3/4" lower.  Depending upon the amount of slope in your line (2% minimum is required for proper operation), you may need to replace several feet of pipe downstream from the valve to average out this "loss" of 3/4" of fall.

*On March 1, 2003, FEMA became part of the U.S. Department of Homeland Security.  FEMA's continuing mission within the new department is to lead the effort to prepare the nation for all hazards and effectively manage federal response and recovery efforts following any national incident. FEMA also initiates proactive mitigation activities, trains first responders, and manages the National Flood Insurance Program and the U.S. Fire Administration.

backflow check valve products



adobe acrobat pdf filesAdapt-A-Valve Brochure (Adobe Acrobat pdf)

Adapt-A-Valve Inspection Chamber

Backwater Valve Diagram
Backwater Valve Features
Back water valves information
Backflow Links
Backflow Preventers
Backwater Valve Animation
Backwater Valve Videos

Basement Drain Backing Up

 contact us about your backwater valve needsContact Us

Flood Alarm

Frequently Asked QuestionsBack water valve questions

adobe acrobat pdf filesFullport Backwater Valve Brochure (Adobe Acrobat pdf)

how to install your backwater valveINSTALLATION TIPS;  how to install backwater valves 

Termex Backwater Valves
Termex Backwater Valve Brochure (Adobe Acrobat pdf)

NEW: TOP-CHECK BACKWATER VALVESnew Top-check backwater valves

Mainline ML-FR4 Backwater Valve (Fio Valve)
adobe acrobat pdf filesML-FR4 Mainline Backwater Valve Fio Valve Brochure (Acrobat pdf)

6" Backwater Valves - Mainline STRAIGHT FIT Backwater Valves

Mainline History

backwater valve measurements and specificationsMeasurements, Specifications and IAPMO Certifications


Mainline Fullport Backwater Valves offer the right solution for your sewer backup problems.


Protect Your Home with a Backwater Valve

All Orders must be placed ONLINE by Credit Card


telephone For non-order info, you may phone Greg at 330.836.9393 9 AM - 4 PM EST M-F
or Voicemail anytime)


copyright 2004 to 7/15/2024 at 11:29:41 ET,
Akron, OH, USA.
All rights reserved.

backflow prevention links is independently owned and resells products produced and manufactured by Mainline of Canada and assumes no liability for the installation of backwater valves and related products.

Be sure to check with the plumbing authority in the municipality in which your valve is to be installed to insure that your installation is in compliance with local code, and be sure have your valve inspected by your local plumbing inspector after installation. Inspect your valve frequently; the Backwater Valve through its clear plastic housing top, and the Adapt-A-Valve, by removing the gate cassette.


Pipe end-to-end, the Adapt-A-Valve takes up 6" of run in your line and the outlet is 1-1/2" LOWER than the inlet, so in just 6" the level of the pipe at the outlet side needs to be 1-1/2" lower.

Pipe end-to-end, the Backwater Valve takes up 12" of run in your line and the outlet is 3/4" LOWER than the inlet, so in just 12" the level of the pipe at the outlet side needs to be 3/4" lower.

Depending upon the amount of slope in your line (2% minimum is required for proper operation), you may need to replace several feet of pipe downstream from the valve to average out this "loss" of fall.

NOTE: New Straight-Fit and ML-FR4 require less slope. (refer to detail pages for these products)


Mainline Valve Warranty
(in printable Adobe Acrobat .pdf file)

visa, mastercard, discover, american express, echeck accepted accepts these
major credit cards plus eCheck
using PayPal's secure checkout.
(No PayPal account needed)
We are unable to process phone orders,
all orders must be placed via the website.
more . . .  

verified paypal business account