Borewell water getting contaminated from a sewage line in vicintiy

We dug the borewell 6-7 yrs back in the compound and the borewell water was being used for washing and bathing by 90 flat holders. Few days back sewage line passing near borewell duct was blocked resulting contamination of sewage water with borewell water. Borewell water became dirty, colour changed and was having bad smell. Now sewage line cleared. Borewell water is coming out with bad odour. Pl suggest the remedy to remove bad odour from borewell water so that members may use the borewell water at least for washing and bathing

Y F. Bagul