Backflow Prevention

Southern Louisiana Water employs full time Backflow Prevention Assembly Testers.
Contact us today for backflow testing for your home or business.

The term backflow means any unwanted flow of used or non-potable water or substance from any domestic, industrial or institutional piping system into the pure, potable water distribution system. The direction of flow under these conditions is in the reverse direction from that intended by the system and normally assumed by the owner of the system. Backflow may be caused by numerous specific conditions; but, basically the reverse pressure gradient may be due to either a loss of pressure in the supply main called backsiphonage, or by the flow from a customer’s pressurized system through an unprotected cross-connection, which is called backpressure. Thus the term backflow covers both a backsiphonage condition and a backpressure condition. A reversal of flow in a distribution main–or in the customer’s system–can be created by any change of system pressure wherein the pressure at the supply point becomes lower than the pressure at the point of use. When this happens in an unprotected situation the water at the point of use will be siphoned back into the system; thus, potentially polluting or contaminating the remainder of the customer’s system. It is also possible that the contaminated or polluted water could continue to backflow into the public distribution system. The point at which it is possible for a non-potable substance to come in contact with the potable drinking water system is called a cross-connection. To prevent backflow from occurring at the point of a cross-connection a backflow prevention assembly must be installed. However, it is important the backflow prevention assembly match the particular hydraulic conditions at that location and is suitable to protect against the degree of hazard present.

A cross-connection is an unprotected actual or potential connection between a potable water system used to supply water for drinking purposes and any source or system containing unapproved water or a substance that is not or cannot be approved as safe, wholesome, and potable. By-pass arrangements, jumper connections, removable sections, swivel or changeover devices, or other devices through which backflow could occur, shall be considered to be cross-connections.

Back-siphonage is caused by mainline piping failures or drafting due to high demands. For example, it is a condition that can occur when the drinking water system pressure drops below that of the fire protection system, drawing the fire protection system water back into the drinking water system.

Backflow prevention devices prevent the flow of non potable (and possibly dangerous) water from your lawn irrigation system or fire sprinkler system into your house and then into the public water supply.

Yes, to keep your family and the community safe these devices need to be checked regularly to be certain they are in working condition.

Check valves and shut-off valves can easily become fouled from debris in the water line, thereby allowing backflow to occur through leaking checks or shut-off valves. In most instances, contamination problems from cross connections and backflow situations are through leaking check valves and/or shut-off valves. Most lawn sprinkler solenoid valves can only withstand low amounts of back-pressure.

Backflow prevention assembly testers routinely find destroyed check valves on lawn sprinkler systems due to water hammer (extreme high back-pressure). The destroyed checks will only be discovered through periodic testing and maintenance programs.

A backflow situation from a lawn sprinkler system can be very difficult and sometimes impossible to detect. Contamination from cross connections and backflow situations will routinely go undetected in the water main due to dilution and will only be discovered when the concentration is high enough to create a taste, color or odor problem and/or when illnesses are reported. Very few backflow incidents have been documented involving lawn irrigation systems. Does this mean backflow is not occurring? No. Water departments routinely shut down water mains throughout the year due to main break repairs, maintenance issues or other reasons. Water pressures are always changing. Irrigation control valves only hold back .5 psi of backpressure and are not to be considered backflow preventers. Any low heads under water upon closing can result in fertilizer and/or fecal matter flowing back into the potable water.

American Backflow Prevention Association – http://www.abpa.org/ Foundation for Cross Connection Control and Hydraulic Research – http://www.usc.edu/dept/fccchr/