Understanding what backflow is, how it occurs, and how to stop potentially dangerous backflow situations will help to avoid problems in your clients' drinking water.
June 4, 2019
Backflow preventers are saving lives across the United States. Sound dramatic? It's really not when you think about the potential danger of consuming water not suitable for drinking. Many states now require the installation of a backflow preventer on every sprinkler irrigation system. A properly installed backflow preventer protects a home's pure drinking water supply by stopping contaminated water from mixing with the drinking water. Understanding what backflow is, how it occurs, and how to stop potentially dangerous backflow situations will help to avoid problems in your clients' drinking water.
What is Backflow and how does it occur?
When nonpotable water or other substances flow through a cross-connection and into the piping of a public water system or consumer's potable water system, it is called backflow. Backflow can be caused by a downstream pressure that is greater than the supply pressure, or by negative pressure (a vacuum). Increases in downstream pressure can be created by pumps, temperature increases in boilers, etc. Reductions in potable water supply pressure occur whenever the amount of water being used exceeds the amount of water being supplied, such as during water line flushing, fire fighting, or breaks in water mains. Backsiphonage (a vacuum) can occur when there is a stoppage of water supply due to nearby fire fighting, a break in a water main, etc.
How can I stop potentially dangerous backflow situations, or avoid them all together?
Irrigation systems make watering lawns and gardens easier and save time, BUT, water that may be contaminated by weed killers and/or fertilizers can backflow into the home's drinking water. Irrigation systems not protected by approved backflow prevention assemblies could endanger the health of a household, neighborhood, or community. Steps can be taken to prevent this dangerous situation.
First, ensure that a proper backflow preventer is installed and maintained. A backflow preventer is a mechanism to prevent backflow, which provides a physical barrier to backflow. The principal types of mechanical backflow preventer are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly. A secondary type of mechanical backflow preventer is the residential dual check valve.
All irrigation systems, new or existing, should be equipped with an approved backflow prevention assembly. Only properly installed, state-approved backflow prevention assemblies meet the plumbing code and provide health protection for family and neighbors.