A water quality test of your well water for coliform bacteria and nitrates, and anything else of local concern. Other typical additional tests are those for iron, manganese, water hardness, sulfides, and other water constituents that cause problems with plumbing, staining, water appearance, and odor. Changes in these constituents also may indicate changes in your well or local groundwater. Additional tests may be recommended if water appears cloudy or oily, if bacterial growth is visible on fixtures, or water treatment devices are not working as they should.