If your well water tests positive for coliform bacteria, don’t worry excessively, yours isn’t the first and it won’t be the last. During well construction and pump placement there are plenty of opportunities for contaminants such as bacteria to enter your well. In most water supply wells a thorough disinfection, or chlorination, of the water supply, if done properly, will kill the bacteria. A follow-up water sample must be collected to ensure this has happened.
If follow-up water sample(s) continue to show the presence of coliform bacteria, further investigation into your well construction may be necessary.