Drinking Water, Cross Connections and You

A cross connection occurs when drinking water is connected to anything else. Something as innocent-looking as a submerged hose can cause adverse health effects to your family or an entire city. There are two types of cross connections:

  • A direct connection occurs when a drinking water hose/pipe is threaded, soldered, welded etc. to anything that can allow another substance to travel back into the drinking water supply by means of backpressure or backsiphonage.
  • An indirect connection occurs when a drinking water hose or pipe (usually open-ended) is connected to or submerged in anything that can allow another substance to travel back into the drinking water supply by backsiphonage only.

Backpressure is when the pressure on the customer side becomes greater than on the water provider’s side. Pumps, elevation differences, steam pressure, and air pressure are common causes of backpressure.

Backsiphonage happens when there is a reduction of pressure in water lines. Water main breaks, operating a fire hydrant  or even flushing a toilet can trigger a reduction in pressure and create backsiphonage (i.e., a vacuum effect).

How can backflow due to either of these effects hurt you, your family, or your community? See Real-Life Backflow Events on page 2 to learn more. If you’re interested in seeing even more examples, please visit www.abpa.org and enter “backflow incidents” into the search field. While you’re there, you can learn more about how to prevent backflow incidents yourself.