Food grade plastics should be a minimum requirement in all hydroponic systems. When designing a home hydroponics set up or buying one from the local hydro shop, check the labels and do your research. If you don’t demand food grade plastics you could be digesting harmful chemicals and toxins with every harvest. It may also be beneficial to your plants to use food grade plastics so they don’t absorb deadly contaminants.
I use plastics with a Number 2 or Number 5 on them for the parts in my own hydroponic setup. Reservoirs, flood trays in a recirculating system, and plant containers are all possible examples of things that require these type of plastics. To find out if your drip lines, water pumps, and emitters are food grade plastic you may have to contact the manufacture. If you are unsure of a product’s quality I would stay away from it until you can do further research. High grade food plastics can also have an FDA approval which should be easy to research.
Remember: Always check the quality of the plastics you are using and double check their qualifications. To clarify the information here I have provided a link to The Daily Green which has an outstanding explanation of the 7 types of plastics.