What is backflow?
It's just what it sounds like: the water is flowing in the opposite direction from its normal flow. With the direction of flow reversed, due to a change in pressures, backflow can allow contaminants to enter our drinking water system through cross-connections. A potentially hazardous cross-connection occurs every time someone uses a garden hose sprayer to apply insecticides or herbicides to their lawn. Another cross-connection occurs when someone uses his or her garden hose to clear a stoppage in their sewer line. Other cross-connections can occur when someone uses his or her garden hose to clear a stoppage in their sewer line; fill a pool while leaving the hose in the water and having an automatic timer set on their hose.
Without a backflow prevention device between your hose and hose bib (spigot or outside faucet), the contents of the hose and anything it is connected to can backflow into the piping system and contaminate your drinking water.
What harm could that cause?
Plenty. When water is delivered to your property it is exposed to many different types of fixtures, including sprinklers, washing machines, hose-bibs, kitchen faucets, tubs, showers, and toilets. For industrial users, the system may be attached to boilers, photo processing equipment, chemical mixing tanks, chillers, water towers, pressure pumps, healthcare and laboratory equipment, etc. Connections between the potable water system and potential sources of pollution, or contamination, are called "cross connections." When backflow occurs through a cross connection, there is a chance that contaminants can be drawn into the public water system.
When does my backflow device need to be tested?
- Air Gaps (AG) shall be inspected at intervals not exceeding one (1) year to ensure that they continue to meet the requirements.
- Double Check Valve Backflow Prevention Assembly (DC) shall be tested at intervals not exceeding one (1) year to ensure that both check valves holds pressure at 2.0 or greater under all pressure differentials.
- Double Check-Detector Backflow Prevention Assembly (DCDA) shall be tested at intervals not exceeding one (1) year to ensure that both check valves hold pressure and do not leak under all pressure differentials.
- Pressure Vacuum Breakers (PVB) shall be tested at intervals not to exceed six (6) months (annually, if installed on an irrigation system) to ensure that the air inlet opens fully when water pressure and the check valve holds closed under pressure.