Water is the Universal Solvent. It picks up a bit of everything it encounters. It is difficult to know what comes into contact with water as it travels over the surface, through the ground and in the air as precipitation. Without proper testing, it is not possible to know the level of water contamination. Are there specific requirements for what type of contaminants are tested for? Most contaminants are invisible and dissolved in water often going undetected ie: Total dissolved solids (TDS), PFAS, Lead, Arsenic, Nitrates, Chemicals, Fertilizers and Pesticides. Testing for some of these contaminants is not easily accessible by the public. Some water treatment equipment has operating water quality parameters which if not met, can impact the quality of drinking water. Rural areas are not subject to the regulations for water the same as cities. When you own a property in the country, you are solely responsible for your own water quality in your home.