New Hampshire Pesticide Practice Test

Anti-siphon devices are designed to prevent backflow of the spray mixture into the water supply. If pressure in the hose drops or the line is submerged, liquid can be siphoned back toward wells, streams, ponds, or other drinking-water sources. The device acts as a one-way valve or backflow preventer, stopping contaminated liquid from entering the water supply while still allowing normal flow to the spray. This protection of water sources is why these devices are often required by regulations or label directions. They don’t affect how well you cover targets, nor do they change tank size or reduce drift—that comes from nozzle selection, spray pressure, and application technique.