Tests for a specific contaminant, group of contaminants, or constituent which signals the presence of something else. Indicator tests are essential for water analysis in order to ascertain more information and come up with appropriate solutions that can treat the existing issues. Using indicator tests for treating specific contaminants will bring the same results for similar contaminants. They are also relatively inexpensive to conduct, but have strict limitations for testing certain water sources such as private wells, and groundwater quality in some states within the United States.