JULY 14, 1997
by Andrew Walgamott
Following state law, the Woodinville Water District is now requiring homeowners with irrigation systems or heating boilers to install and routinely check backflow prevention devices. The devices, called double check valves, prevent cross connections. Cross connections are incidents when non-potable water is sucked back into drinking water supplies, contaminating the system with chemicals, yard waste, insects or other health hazards.
"This is strictly a public health and safety issue," said Bob Bandarra, Woodinville Water District general manager.
State law dictates the district shut off non-complying customers water supply, though district officials have said they will be working with its customers needs. According to district figures, 1,500 of 12,000 Woodinville-area customers have in-ground irrigation systems. Bandarra said that of 425 systems checked so far, only 9 or 10 have had to install double check valves. He estimated the cost of parts and installation by a certified plumber at $200-$250.
An initial test of the system is also required by state law. Bandarra said if the valve was new, the district would test it for free. If the valve was already installed, a state certified backflow tester needs to check the device. Also required by the state is a yearly test of the valve. The district has a list of testers, and estimates costs to be between $30-$120 depending on the company. More than 1,000 industrial customers already have double check valves and other protection installed in their systems. Customers have complained about the requirement and cost of installation, mistakenly thinking the district is making a profit from the requirement. The district insists it is not gouging residents and is only following state law.
"We don't make anything. We make zero. We're mandated by the state to do this program," said Ken King, maintenance and operations manager.
In 1970, the state enacted legislation requiring double check valves on plumbing following incidents in Massachusetts and Connecticut where entire football teams were stricken by hepatitis after drinking water that had been contaminated when it was back-siphoned from open pits and fields sprayed with chemicals. During a 1992 drought, a Hollywood Hill resident hooked up his sprinkler system to an old well and eventually contaminated the water supplies of five neighbors.
The law was revised in 1992 and is currently being studied in committee to determine if it is stringent enough.
Locally, water district officials fear that a sudden hydrant draw-down due to a fire could siphon water off of a lawn through an irrigation system and into public water supplies.
Customers have also said the risk of back flow was extremely low. There have been 18 reported incidents of back flows since 1969.
Although the risk seems minimal, a lawsuit filed against a water district in Virginia following a back siphonage of the insecticide Chlordane was settled for $13,000,000 in 1985.
"If one customer is injured or impaired, it's too much to risk," Bandarra said. He noted that the first persons injured from a back flow incident were residents of the home where it occurred and the immediate neighbors. He said the alternative to making residents with irrigation or heating boilers pay for the backflow preventers was to pass the cost along district-wide.
The district will be sending out letters informing its customers of the requirements.