What is backflow?
Backflow is the flow of water in the reverse direction from the intended direction of flow in a piping system.
This may occur because of a difference in pressure within the drinking supply line. The most common type of backflow is back-siphonage.
This is a negative pressure in the water line, back-siphonage is caused by a sudden drop in pressure of the water supply.
Listed are the most common causes of back-siphonage:
- A break in the water line
- Lowered main water supply pressure due to fire or flushing of the water main
- Reduced water supply pressure on the suction side of a booster pump
The most common cross connections are:
- Garden hoses * see below
- Swimming pools
- Wading pools
- Boilers
- Lawn irrigation system ** See below
- Hot water recirculating lines
- Crossed water lines in a piping system
Outdoor
Faucet
The ordinary garden hose is the most common way to contaminate the water supply. This can happen when one end of the hose is attached to an outdoor faucet (sill cock), and the other end is connected to an aspirator type bottle, insecticides or other chemicals in the aspirator
bottle can be siphoned back into the drinking water supply.
Lawn
Irrigation System
Lawn
irrigation systems need a vacuum breaker backflow
preventer to protect against lawn and pesticide
chemicals being drawn in from the lawn and back into
the drinking water supply.
