If you have not yet done so, discontinue using the water for drinking, preparing food or making ice, and use bottled water instead.
The well should be inspected for any damage or normal wear and tear that could allow contamination. If no damage is present or after repairs are done, the well can be disinfected to eliminate the bacterial contamination.
Water should be retested and shown to be free of total coliform before consumption. If continued testing is also positive, treatments systems such as ultraviolet (UV) or chlorination should be considered.