Backflow prevention & cross-connections

Some farmers believe that backflow preventers are required only if they are getting agricultural water rates. This is untrue.  ALL FARMS in Hawaii, connected to a public water system in some way, must have an APPROVED, MAINTAINED and ANNUALLY tested backflow preventer.

Example of a backflow assembly and how it is hooked up on a farm.

According to the EPA Safe Drinking Water Act of 1974 (SDWA), US farms (and many other businesses and residents) are required to have backflow preventers on their water systems that have cross-connections to a public water source. Pathogens, fertilizers, pesticides, rust and other farm contamination could be sucked into a public water system should a farm water system experience a reverse in the water direction due to “back-siphonage” (which could occur, for example, if the fire department had to draw a significant amount of water from a hydrant near a farm to fight a home or brush fire) or “back-pressure” resulting from more pressure than the potable source it is connected to. While the chances of these problems happening is relatively small, one occurrence could contaminate a large community water source.  A good overview on this issue can be found here.  In Hawaii, all counties follow and enforce the SDWA.  Also, on Good Agricultural Practices audits, there is at least one question about a backflow preventer on a farm/ranch or in a packinghouse/processor.  Click on the links below to see specifically how your county administers the SDWA.