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Cross Connection Control Plan
What is San Bruno’s Cross Connection Control Plan and Program
San Bruno protects its potable water system from contamination from customers through its Cross Connection Control Policy Handbook. The main objectives are:
- Prevent contaminants such as chemicals, bacteria, or other pollutants from entering the drinking water system.
- Inspect water service connections and plumbing systems to locate potential cross-connections and ensure they are properly controlled or removed.
- Require approved backflow prevention devices to be installed where hazards exist and ensure they are tested and maintained regularly in partnership with San Mateo County Environmental Health Services Division
- Follow applicable laws and regulations that require public water systems to maintain a cross-connection control program.
- Provide information and guidance to residents, businesses, and contractors about their role in protecting the public water supply.
What is a Cross Connection
A cross-connection is a point where clean drinking water could come into contact with non-drinking water or other substances. If not properly protected, this connection could allow contaminants to enter the drinking water system. Some examples are:
- Garden hoses placed in pools, buckets, or chemical containers
- Irrigation or sprinkler systems connected to household plumbing
- Boilers or heating systems connected to the water supply
- Commercial equipment that uses water
- Private wells connected to plumbing that also receives city water
What is Backflow
Backflow occurs when water flows in the opposite direction than intended in a plumbing system. Instead of clean drinking water moving from the public water system into homes and businesses, water can flow backward and potentially carry contaminants into the drinking water supply.
Backflow usually happens when there is a change in water pressure in the system. For example, if pressure drops in the main water line—such as during firefighting, a water main break, or heavy water use—water from hoses, irrigation systems, or other connections could be pulled back into the drinking water system.
To prevent this, backflow prevention devices are installed on certain plumbing systems to ensure water flows in only one direction and to help protect the public water supply.
How to Prevent Backflow
Certain plumbing systems, such as irrigation systems, fire sprinklers, or commercial equipment, may be required to have a backflow prevention device installed. These devices are designed to allow water to flow in only one direction and prevent contaminated water from flowing back into the drinking water supply.
An air gap is a simple and effective way to prevent backflow. It is the physical space between a water outlet (such as a faucet or hose) and the highest possible water level of a container, sink, or pool. This gap prevents contaminated water from being drawn back into the plumbing system.
Backflow prevention devices must be installed correctly and maintained to ensure they work properly. In many cases, these devices are required to be tested annually by a certified backflow tester. A list of certified backflow testers can be found on the San Mateo County Cross Connection Control website.