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50 Ways Farmers Can Protect Their Groundwater
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29. Prevent Backsiphoning

Backsiphoning

Backsiphoning is the equivalent of pouring pesticide solution directly into your water supply. It is a major problem. Fortunately, it is easy to prevent.

Backsiphoning can occur when you mistakenly leave the end of the fill hose below the level of the pesticide solution in the spray tank. If the water flow is inadvertently shut off, the pesticide solution could back up through the fill hose and get into the water supply.

Backsiphoning  prevention To prevent backsiphoning, fill the spray tank with water first. If you must add the pesticide first, make sure the water hose is secured above the tank and out of the pesticide solution. Maintain a 6-inch air gap between the hose and the tank opening. If necessary, mount a clamp on top of the tank to hold the hose.
tank filling diagram Also, fill the tank from a hydrant that is at least 100 feet away from the wellhead. If the hydrant is closer, use a hose that is long enough to stretch at least 100 feet from the well.
anti-backflow device Always use anti-backflow devices, such as check valves, on pumping equipment. You can buy inexpensive anti-backflow devices from suppliers of irrigation or sprayer equipment.
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