Our water tanks are manufactured using resins that meet FDA specifications to ensure safe storage of potable water. The black or dark green color limits light penetration which reduces the growth of water-borne algae. These tanks are rated at 9.2 pounds per gallon, which means that they are for WATER STORAGE ONLY! They should not be used for chemicals, fertilizers or any other product. Where applicable, the tanks will carry the NSF approval. Please contact your distributor for more specific information regarding NSF approval.