Cross-Connections & Backflow

Important Safeguards
Minimization of cross-connections and backflow prevention are important safeguards for protecting our drinking water system from accidental pollution. Cross-connections occur when ever a potable water pipe is directly or indirectly connected to a piece of equipment, piping, or container of non-potable water or other liquid. Backflow is the flow non-potable water or other liquid into a potable water pipe through a cross-connection. Read more about cross-connections, backflow, and your role in protecting drinking water here.

Wide Range of Pollutants
Backflow through a cross-connection can introduce a wide range of pollutants into your home drinking water pipes, and in some cases, into the community drinking water system. In May 2014, our customers received a notice in the mail that the City’s drinking water system had violated the State maximum contaminant level for Total Coliform bacteria. Total Coliform are naturally in the environment and generally not harmful themselves but are used as an indicator that other, potentially harmful bacteria may be present. Whenever we find Total Coliform in a sample we concurrently test for E. coli, a disease causing bacteria. We did not find E. coli in any drinking water samples. Corrective action was taken to flush the Total Coliform bacteria out of the drinking water system and subsequent testing showed Total Coliform was no longer present in the drinking water system.

Example of Backflow
During its investigation of this incident, the City found some evidence to suggest that the source of total Coliform in the distribution system was from a cross-connection. In this case, it is suspected that a hose connected to a spigot was submerged in a decorative fish pond while the pond was filling. Non-potable water from the fish pond may have back-flowed through the cross-connection and introduced Total Coliform bacteria into the distribution system. While this incident was not an emergency, it does highlight the point that we all have a responsibility to protect our drinking water resources. Please take a moment to learn about cross-connections and backflow, and to identify and eliminate any existing cross-connections at your home or business.