Cross Connection Control Guide
A cross-connection is defined as any actual connection or arrangement between any pipe conveying potable water from a public water system and any non-potable water supply, piping arrangement or equipment including, but not limited to waste pipe, sewer, drain, or other unapproved sources, or any direct or indirect connection between a plumbing fixture or device whereby contaminated water or fluids, gasses or substances may enter and flow back into the potable water piping system or the distribution system of a public water system.
This guide discusses the importance of controlling cross-connections and preventing backflow occurrences from unprotected cross-connections in the water system.
1. Key Cross-Connection Terms and Definitions
Backflow - The flow of water or other liquids, mixtures, or substances into the distributing pipes of a potable water supply from any source or sources other than its intended source. Back-siphonage is one type of backflow.
Back pressure - Backflow that occurs when the pressure in an unprotected downstream piping system exceeds the pressure in the supply piping.
Back-siphonage - Resulting from negative pressures in the distributing pipes of a potable water supply.
2. Where Can Cross-Connections Occur?
Cross-connections can occur at many points throughout a distribution system and a community's plumbing infrastructure. Cross-connections can be identified by looking for physical interconnections (or arrangements) between a customer's plumbing and the water system. Some specific examples of backflow incidents that can occur are:
- Lawn chemicals back flowing (back-siphoning) through a garden hose into indoor plumbing and potentially into the distribution system.
- Back-siphonage of "blue water" from a toilet into a building's water supply.
- Carbonated water from a restaurant's soda dispenser entering a water system due to backpressure.
- Back-siphonage of stagnant water in fire suppression systems into the distribution system.
- Back-siphonage of chemicals from industrial buildings into distribution system mains.
- Backflow of boiler corrosion control chemicals into an office building's water supply.
3. Cross-Connection Control and Backflow Prevention Programs
Why is it Important to Have a Cross-Connection Control and Backflow Prevention Program?
Controlling cross-connections and preventing backflow is critical to ensuring the safety of your drinking water because:
- Cross-connections are ever-present dangers that exist in most water systems and can result in serious chemical or microbiological contamination events in drinking water systems.
- Cross-connections should be protected in order to prevent backflow, which can be hard to detect.
- In any distribution system, potential cross-connections and therefore sources of contamination can be numerous, varied, and unpredictable.
- Having these programs in place can help you avoid the costs of responding to a contamination incident.
4. Lynn Water and Sewer’s Cross-Connection Control Program
On new installations, the Commission will provide on-site evaluation and/or inspection of plans in order to determine the type of backflow preventer, if any, that will be required. This plan review takes place with the submission of a Design Data Sheet (under the Forms and Documents tab). Installation of the device shall not be performed until an approval letter has been issued by the Commission.
The Commission is responsible for inspecting all industrial, commercial, and institutional premises served and to determine whether cross connections exist and whether all cross connections are either properly protected by an appropriate control device or eliminated.