For years, working as a contractor for the City of Edmonton, plumber and gasfitter Gabe Coscarella saw first-hand the damage to a home that can happen from sewer backup and flooding.

"We'd go in after the fact, when sewers had backed up, and we'd install valves to try to prevent the problem from happening again," he says. He and his crew used to do about 200 to 300 retrofit valve installations a year. Coscarella figured there had to be a better way to stop the sewer backflow and subsequent flooding from occurring in the first place.

"One day I was just sitting at my table and came up with this idea for a valve and drew it out," he recalls. That sketch led to Coscarella becoming an award-winning innovator and president of his own successful plumbing equipment company, Mainline Backflow Products Inc. of Edmonton.

At the time Coscarella sketched his idea, the National Plumbing Code of Canada required homes at risk of a sewer backflow to be protected by valves on each of the sewer branch lines in a house.

Picture your house as a tree with several branches. There's one wastewater line for your bathroom, for example, one for your clothes washing machine, one for your basement floor drain, and so on.

The problem with this branch-line protection approach, Coscarella says, is that the backflow valves on each of the sewer branch lines are scattered around the basement and are typically covered up by walls, flooring and carpeting. These valves are normally installed closed to prevent reverse flow. So if one plugs up and the homeowner runs a cleaning sewer auger or 'snake' through it, the cable can get snagged on the valve gate and rip it out. "Nobody knows about it and you've got more problems."

Coscarella's innovation changed the way buildings are protected from sewer backflow.

Instead of having a normally closed valve on each sewer branch line, the Mainline Fullport Backwater Valve installs directly on the main sewer line coming into the house, in a normally open or "fullport" position. "We don't have to protect any of the branches anymore. One valve protects the entire building."

But at the time Coscarella was developing his valve, the National Plumbing Code of Canada didn't allow the normally closed valves on the mainline, because the code required a free-flowing circulation of air between the building's drainage system and the municipal sewer line, in case of gas build-up.

Mainline's Fullport Backwater Valve, with its normally open design, allows this circulation of air. The valve's unique venting properties enabled Coscarella and Mainline to convince the industry and government regulators to change the National Plumbing Code of Canada in 1998, allowing buildings for the first time to be protected by one normally opened valve on the main sewer line.

Coscarella built his first prototype out of Plexiglas and Tupperware, and obtained a patent on it.

He formed Mainline and attracted shareholders, enabling the company to build its first working valve. It was rigorously tested at the Northern Alberta Institute of Technology in Edmonton. The valve was subjected to flushes with abrasive silica sand ('ashtray sand') and improvements made.

"We had to build a valve that would work around sewage," Coscarella explains. It had to allow for the free flow of wastewater, yet close quickly to prevent backflow from a sewer backup.

The resulting valve, which Mainline began selling in 1997, has interior flow channels that direct the normal flow of wastewater through and out of it, which helps keep the valve clean. A gate, hinged on the bottom of the valve, is normally kept open by gravity. This gate is fitted with tiny, water-impervious floats. When the sewer starts to back up, water rises in the body of the valve and the gate starts to float or lift, being pushed by the reversed flow of water into the closed position.

The valve has a built-in main sewer cleanout, allowing cleaning sewer augers or 'snakes' to easily pass over the open gate and be retracted without damaging the gate or other components. The rugged, injection-molded valve also has a transparent lid for easy visual inspection.

There are now more than 130,000 Mainline Fullport Backwater Valves installed in buildings across North America, Coscarella says proudly.

In existing homes, where the valve is retrofitted onto the main sewer line, there must be a sufficient grade or slope in the mainline for the valve to function well, he notes. If the line isn't changed to provide sufficient grade, it could cause potential problems. But these cases are extremely rare.

"In Alberta, every building has to be protected," Coscarella says. "Our valve goes into about 95 per cent of the homes in western Canada. In new homes, we've never had a valve failure.

The Canadian Institute of Plumbing and Heating voted Mainline's valve the most innovative product of 1997, and the valve went on to win the institute's coveted Ivan R. Leger Award.

The company's fullport valves are also making inroads in Quebec, although Ontario has been resistant in adopting the new approach in the National Plumbing Code of Canada.

Mainline also makes its Adapt-A-Valve, which can be easily converted to be installed on the main line either normally open or normally closed, for the U.S. market, which is more familiar with the normally closed-type type. But the fullport valve is becoming more popular south of the border, too, says Coscarella, noting that Mainline's valve sales are split evenly between the normally open and the normally closed types. The company's product for the U.S., where a building's sewer system is required to be tested upon installation, also can be fitted with a gate that slides into the same valve body, isolating the system for testing.

In the early days, Coscarella tapped small grants from the National Research Council of Canada's Industrial Research and Assistance Program and the federal Scientific Research and Experimental Development tax credits program. But once his product hit the market, sales took off.

Mainline is now selling, mainly through wholesale plumbing outlets, about 30,000 valves a year in Canada and the U.S. Tom Crerar, Vice-president of Sales and Marketing, manages a sales agent network that stretches across Canada and into California, Nevada and Arizona.

The company has stayed small and lean in Edmonton. Production Manager Sergio Saporito supervises five full-time employees in the summer to assemble and ship products. Mainline contracts the injection molding of its valve in various sizes to another Edmonton company, STAMCO (Specialty Tool and Manufacturing Co.), helping to provide jobs for another eight people.

Mainline is continuously developing new products, such as a soon-to-be-available insertable valve, to meet the industry's needs. The company sold more than 40,000 valves last year in Canada, the U.S. and the U.K., and is expecting 30-per-cent growth this year, with plans to expand sales into Australia. Mainline's innovations are attracting attention from Canada's biggest plumbing equipment firms, which are interested in potential product-distribution partnerships.

Coscarella says he expects that winning the Manning Innovation Award will bring more attention to Mainline, "It is a prestigious award and I'm honoured to have received such an award."

This year, Manning Innovation Awards presents $145,000 in prize money distributed among four leading Canadian innovators, as well as $20,000 among eight Canada-Wide Science Fair winners. Since 1982, the Foundation has awarded $3.5 million to recognize and reward Ca