Chemigation valve
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. 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. Some governments require the use of two chemigation valves installed in series if hazardous chemicals are to be injected.
The following policies require or encourage the installation of these valves:
Texas State law Chapter 344.73 in Subchapter D - 1.
Florida [Department of Agriculture and Consumer Services|Florida's Department of Agriculture and Consumer Services] Water Quality/Quantity Best Management Practices for Florida Specialty Fruit and Nut Crops p. 20 specifies that: