Routine testing for a few of the most common contaminants is highly recommended. Even if you currently have a safe, pure water supply, regular testing can be valuable because it establishes a record of water quality. This record can be helpful in solving any future problems and in obtaining compensation if someone damages your water supply. Testing needs to be performed by certified testing laboratory using USEPA methods of collection, storage and testing. Unbiased testing needs to be established and has more validity in court proceedings to establish responsibility.
Taraba, Joseph L.; Ilvento, Tom; Heaton, Linda; Herbst, Bob; Thomas, Grant; and Crum, Dwight, "Home Water Testing" (1986). Agricultural Engineering Extension Updates. 34.