Backflow/Cross Connection

The term “cross-connection” means any unprotected actual or potential connection or structural arrangement between a public or a consumer’s potable water system and any other source or system through which it is possible to introduce into any part of the potable system any used water, industrial fluid, gas, or substance other than the intended potable water with which the system is supplied. Simply stated, it is a connection between the potable (drinking) water supply and a source of contamination, which may under certain circumstances enter the drinking water system.

What is backflow?

The term “backflow” means the undesirable reversal of flow of water or mixtures of water and other liquids, gases or other substances into the distribution pipes of the potable supply of water from any source or sources. Simply stated, the entry of contaminants into the water supply is called “backflow”.

Backflow occurs when a “backsiphonage” or “backpressure” condition is created in a water line. Backsiphonage may occur when the pressure in the drinking water system drops creating a vacuum or partial vacuum in the supply piping. Backpressure may be created when a source of pressure, such as a pump or a pressure type chemical injector, creates a pressure greater than that in the drinking water system.

The El Toro Water District is required by Title 17, California Code of Regulations to administer a Cross-Connection Control Program to protect the public water system.

A goal of the District’s Cross-Connection Control Program is educating the public as to the importance of backflow prevention and to exercise reasonable vigilance to ensure that the consumer has taken the proper steps to protect the public potable water system.

OC Health Care Agency Environmental Health – Cross Connection Website

Backflow Prevention Device Testers

ETWD Blank Backflow Test Form PDF

ETWD Backflow Test Form – Blank PDF

Questions relating to backflow prevention:

Steve Wingen, ETWD Cross Connection Specialist                                                   (949) 837-7050, Extension 209.

Completed test forms can be emailed to