Charleston Water System’s Cross-Connection Control program exists to protect our public water system against potential contamination from backflow.
Backflow is the reversal of the normal flow of water. It can happen when a drastic change in water pressure occurs.
If a source of contamination is connected to a plumbing system when backflow occurs—such as a fertilizer dispenser on a hose—those contaminants could get siphoned back into the home or building's plumbing system, and potentially, our public water lines.
That's why state and federal regulations require water systems to identify cross connections between the public water system and private plumbing systems and take steps to prevent backflow through these cross connections.
Watch a video explaining backflow (1:55)
Our Backflow Requirements
Charleston Water System requires customers whose operations present a potential backflow hazard to install, maintain and annually test a backflow prevention assembly that meets our specifications.
Our inspectors identify customer connections that may present a backflow hazard, such as businesses, manufacturing facilities, and in-ground irrigation systems. We then contact those customers and ask them to complete a form that provides the information we need to determine the degree of backflow hazard and what type of backflow prevention device should be installed.
Charleston Water System does not install or test backflow preventers. Customers are responsible for having backflow preventers installed according to our specifications and tested annually by one of our approved testers.
Our Cross Connection Control Inspectors inspect assemblies after they're installed and are available to answer customers’ questions about backflow prevention.
What is a cross connection? A cross connection is a link between a potable water system and a non-potable water system—in our case, Charleston Water’s public water lines and our customers’ private plumbing systems. Backflow can occur through cross-connections.
What is backflow? Backflow is the reversal of the normal flow of water. It can happen as a result of water pressure differences or sudden changes in pressure and can allow contaminants to get siphoned back into buildings’ plumbing systems, and potentially, the public water supply. There are two types of backflow - back pressure backflow and back siphonage backflow.
What can cause backflow? Backflow can be caused by a sudden drop in the water pressure in a public water main, which can create a sub-atmospheric condition.
For example, If a drop in pressure occurs while a hose is in a bucket of dirty water, that water could be sucked back into the public water system, potentially contaminating the water for other users. A drop in pressure could be caused by a variety of things, including a water main break, loss of power at a pump station, etc. Backflow preventers keep this from happening.
What does Charleston Water System do to prevent backflow? Since 1985, Charleston Water System has installed residential dual check valves on every residential water service. Charleston Water System also requires a testable backflow prevention assembly appropriate for the degree of hazard. Charleston Water System also conforms to the provisions of the 2000 International Plumbing Code (IPC).
Backflow prevention assemblies prevent water from re-entering the public water supply during a loss of system pressure. Charleston Water System is supportive of the American Backflow Prevention Association (ABPA). The ABPA is the world's largest organization dedicated to educating the public on how to prevent backflow.
What can I do to prevent backflow? You can prevent backflow in your home plumbing system by installing an inexpensive hose-bib vacuum breaker on each of your outside water spigots.
These vacuum breakers will prevent water from being back-siphoned from a polluted or even contaminated water source into your home's water pipes or the public water distribution system. These devices cost about $7 and are available at most hardware stores. Hose-bib vacuum breakers have been required by the Standard Plumbing Code since 1963.
Typical backflow preventer
for a residential irrigation system. Backflow preventers protect Charleston Water System's public water supply from potential contamination by blocking backflow.
