The National Ground Water Association (NGWA) recommends well owners test their water at least annually for bacteria, nitrates, and any contaminants of local concern. More frequent testing should be considered if:

• There is a change in the taste, odor, or appearance of the well water, or if a problem occurs, such as a broken well cap, inundation by floodwaters, or a new contamination source

• The well has a history of bacterial contamination

• The septic system has recently malfunctioned

• Family members or house guests have recurrent incidents of gastrointestinal illness

• An infant is living in the home, or

• To monitor the efficiency and performance of home water treatment equipment.