The National Ground Water Association (NGWA) recommends well owners test their water annually for bacteria, nitrates, arsenic 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
To monitor the efficiency and performance of home water treatment equipment.