I notice when I turn my frostless hydrant off with the hose connected, it siphons most if not all water from the hose. I am worried of potential plastic chemicals in the hose after it sits out in the sun leaching into my well water after the hydrant siphons the water all out - especially when I get around to installing drip irrigation systems.

Will a simple $5 plastic backflow preventer be all I need, or is there a certain product meant just for this? I will potentially be drinking the same water that flows back in the well after the frostless hydrant is shut off - yes?