http://Baumbach.com Information about Baumbach plumbing, the first women master plumber in the World, Baumbach's looking for Baumbach's, the history of Baumbach plumbing from Arlington Virginia and Fairfax Virginia, the history of the Baumbach family name and much more...

http://www.baumbach.com/history/lillian.htm Lillian Ann Baumbach First Woman Master Plumber.

www.valvulas-var.com.co prevent  backflows in any type of sewage system. An efficient alternate solution where check or flap valves are not appropriate. Website is in Spanish.

American Society of Sanitary Engineering  promotion of health, welfare and better sanitary engineering principles. The organizations motto is "Prevention Rather than Cure."

www.pmmag.com Plumbing & Mechanical Online.

http://www.petersonvalve.com Now you can protect your home from expensive damage caused by wastewater backups while controlling expensive installation costs, maintenance and problems associated with typical waste backwater valves.

There is a other company called General Wire and Spring  aka General Pipe Cleaners that has something that will work on 2 floor drains http://www.generalpipecleaners.com/ they do not have it listed on their web site but they do sell it, call and ask them.