A cross connection is any actual or
potential physical connection between our drinking water and anything that could
pollute or contaminate the water supply. For example, food and beverage
processing equipment, without backflow preventers, has the potential for
backflow to occur and contaminate the water supply.
Backflow is the undesirable reversal of flow of non-potable water or
other contaminants through a cross connection and into the water
distribution system. When the flow is reversed or "backflow" occurs, contaminated water
can flow backward, drawing a contaminant into the water supply. There are
two types of backflow - backpressure and backsiphonage.
Backflow is typically caused when an unforeseen change in water pressure
allows the water to flow in reverse of the normal direction in the water
from a contaminated source to a drinking water supply. A drop in pressure
could be caused by a variety of circumstances, including a water main break
or the need to fight a fire.
To prevent backflow of contaminates, the City of Bellingham Water
Utility follows all cross-connection requirements of the
State Department of Health. Installation of specific backflow protection
assemblies and annual testing are required according to currently adopted
Washington Administrative Code.
Possible cross-connection locations
Some places that can result in cross-connection issues include:
- Irrigation or lawn sprinkler equipment
- Food and beverage equipment
- Wash basins and service sinks
- Laboratory equipment
- Fire sprinkler systems
- Chemical feed equipment
For answers to specific cross-connection control questions, contact the
Cross-Connection Control Specialists at the Operations Division of the Public Works Department.