What precaution should be taken to protect the water supply when handling pesticides?

Using an air gap or antisiphoning device is essential in protecting the water supply when handling pesticides because these methods create a physical separation that prevents pesticides from being back-siphoned into the water system. This is particularly important during the mixing and application of pesticides, as it ensures that any accidental spill or overflow cannot contaminate the water source.

An air gap is a vertical space that prevents any potential for fluid in a container or tank to flow back into the potable water supply. Similarly, an antisiphoning device helps to maintain this safe barrier, ensuring that pesticide solutions do not enter the water supply under any conditions, such as a drop in water pressure.

Other measures, like installing a filtration system or conducting regular water quality tests, while valuable in their own contexts, do not provide the immediate physical safeguard against contamination that an air gap or antisiphoning device does during pesticide handling. Using only organic pesticides may reduce the risk of chemical contamination, but it does not eliminate the need for effective physical barriers during the application process.