Sometimes called a check valve or a backflow preventer, a chemigation valve is an apparatus designed to protect water supplies from agricultural chemicals used during chemigation, the application of chemicals such as fertilizers and pesticides through irrigation water.[1] Most chemigation valves consist of a spring-loaded check valve, a low pressure drain, an air and vacuum relief valve, and an injection port for introducing the chemicals downstream of the check valve. Many chemigation valves also have a 4-inch inspection port so that a person can reach inside and feel if the check valve is still functional[citation needed]. Some governments require the use of two chemigation valves installed in series if hazardous chemicals are to be injected[citation needed].
The following policies require or encourage the installation of these valves:
Texas State law Chapter 344.73 in Subchapter D - 1.(b) [citation needed]
Florida's Department of Agriculture and Consumer Services Water Quality/Quantity Best Management Practices for Florida Specialty Fruit and Nut Crops [2] p. 20 specifies that: