Unlike a municipal water service, homeowners with water wells have the responsibility of testing and treating their water supply. If you are purchasing a new home, testing the water well provides you information on the quality of the groundwater and informs you of expenses related to treatment and filtration that may be needed to keep your family safe. It's important to note that just because water tastes and smells normal it may not be safe. Contaminants such as arsenic are tasteless and odorless and remain undetected unless tested for. Water changes as it moves through the ground, picking up a variety of minerals and possible contaminants, turning to its composition over time. Annual testing and maintenance is the only guarantee of safety.