Illinois drinking water supplies are protected by both the Illinois Environmental Protection Agency (IEPA) and the Illinois Department of Public Health (IDPH). IEPA regulates public water suppliers, while IDPH regulates plumbing and waste facilities on private property. Together, these two agencies provide protection for the drinking water supply which extends from the source of supply to the ultimate drinking water consumer.
The Federal Clean Water Act requires the public water supply to be protected from contamination by outside sources. A Backflow Prevention Program minimizes the possibility for the water-using public to inadvertently contaminate or pollute the domestic water system.
Backflow is the unintended reverse flow of a liquid or gaseous substance within or connected to a drinking water piping system. Back-siphonage is the reversal of normal flow in a system caused by a negative pressure vacuum or partial vacuum in the supply piping.
Anytime a substance which does not meet all state and federal standards for safe drinking water is connected to the potable water supply without proper protection, a cross-connection exists. Cross-connections are arrangements in a piping line which allow the potable water supply to be connected to a line which contains a contaminant. They do not jeopardize the safety of a drinking water system until backflow occurs. Once proper backflow protection is installed and maintained on the connection between the drinking water supply system and the nonpotable substance, the drinking water system is safe.
A simple example of a potential cross connection is a lawn irrigation system where fertilizers, chemicals, or other contaminants can come into contact with the potable water supply through the irrigation heads. Another example would be a garden hose connected to a house faucet on one side and a pesticide spray bottle on the other side.
There are various types of backflow prevention devices used today. The type of device is determined by the degree of the hazard presented by the possible cross-connection.