Frequently Asked Questions

Backflow is water flowing in the opposite direction from its normal flow. CVWD potable water system is designed to keep the water flowing to our customers. When hydraulic conditions within any water system deviate from “normal,” the direction of water flow can be reversed. This creates a backflow condition and the potential for contaminated water entering the potable water distribution system.

A cross-connection is a permanent or temporary connection between potable drinking water and anything that can pollute or contaminate the water supply.

There are two ways in which backflow can occur:

• Backsiphonage: Backsiphonage can occur when there is a sudden reduction in the water pressure of the distribution system, such as during firefighting or when a water main breaks. At these occurrences, water flow can be reversed. This reversal can create a suction effect and draw potential contaminants into the potable (drinking) water system.
• Backpressure Backpressure is created when pressure in the customer’s water system exceeds the pressure in the potable (drinking) water system. This can force the potable water to reverse its direction of flow through a cross-connection between the two systems. Potential contaminants can then enter the potable water system.

A backflow prevention assembly is an approved, testable assembly, which uses check valves and/or relief valves in different configurations, to prevent potential contaminants from flowing into the potable (drinking) water system. An approved backflow prevention assembly has gone through an approval process at the Foundation for Cross-Connection Control and Hydraulic Research (USC FCCC&HR) at the University of Southern California. This is a two-step process of laboratory tests and a 12-month field test. Only assemblies successfully completing the entire testing process are recognized by the district as approved backflow prevention assemblies.

State and Federal law requires that water suppliers protect their potable water systems from contamination. When a determination is made, either by plan check and/or inspection, that the potable (drinking) water system may be subject to contamination through a backflow condition, the customer will be notified and required to install an approved backflow prevention assembly.

The district makes these decisions based on a case-by-case basis. Residential, commercial, and industrial customers demonstrating a high potential for contaminants to enter the potable water system must install, test, and maintain backflow prevention assemblies.

Only certified backflow prevention assembly tester’s appearing on the district’s list of approved backflow prevention assembly testers may test or repair the assemblies within the district’s jurisdiction. These testers have shown their competency to test backflow prevention assemblies to the San Bernardino County Division of Environmental Health Services and carry a wallet card to prove this. Once the tester has completed the testing, then the original Test and Maintenance Report must be returned to the district.