Information for WCSA water customers pertaining to cross-connection and backflow prevention
In past years Washington County Service Authority mailed each water customer a cross connection survey. We were very pleased that a large portion of our over 50,000 customers took time to return the surveys. We also had many customers phone the office with questions pertaining to their respective plumbing systems. WCSA was impressed with the degree of interest the community took in this matter and would like to refresh our water customers at this time.
Modern Water Treatment Plants do a terrific job of cleaning and disinfecting raw water sources. Recent case studies of water contamination have found that contaminants have found their way into the water supply out on the distribution system, not at the treatment facility.
A Cross-Connection is any temporary or permanent connection between a potable (i.e. drinking) water system and any source or system containing non-potable water or other fluid. These occurrences can be as obvious as an un-protected potable water line entering a Waste Water Treatment Plant or as innocent looking as a garden hose left immersed in a bucket of cleaning solution.
Under normal operating pressures these cross-connections may not present a threat to the drinking water supply. The problem occurs any time pressure becomes lower on the potable or public supply side than it is on the non-potable side. Contaminants can reverse flow by either back siphonage or back pressure.
Back siphonage can occur when county water line pressure is greatly reduced by a line break or under conditions of high usages such as a fire flow. Non-potable substances can be sucked back out to the water main through any existing cross-connection. For example: A 6” water main develops a leak. Our crews have to cut off water service on that 6” line in order to repair the leak. As the remaining water in the line flows out of the leak, water in un-protected homes and businesses reverses flow. At this point something toxic could find its way to the public water system.
Back Pressure can occur when pressure on the customer’s side overcomes normal operating pressure on WCSA’s side. Boilers and water pumps are a couple of examples that could create a situation were customer-side pressure could force contaminants back into the public water system. New WCSA customers that previously had a well or spring with associated pumps and pressure tanks could be a source of back flow due to back pressure. WCSA must insist that customers served by new line extensions provide proof of physical disconnection between their old private water systems and the WCSA system.
A WCSA representative can inspect the customers system if deemed necessary before service is established.
Thanks for taking time to look at this issue. Keep in mind that the first folks you are protecting by taking measures to prevent backflow are members of your own household.
If you have more questions about cross-connections or backflow please call WCSA or log on to the following websites.
Virginia Cross Connection Control Association
USC Foundation for Cross-Connection Control and Hydraulic Research
American Backflow Prevention Association