Drange water Problem

hello sir,
we have also a borewell issue before some time our casing pipe is damaged my mouse so we change aal the casing pipe with pvc pipes aprrox 100 ft. then after 1-2 month the water is pure but now again same problem arise and smelly water comes and smell like a drange water.

What can i Do please suggest me.

You need to specify if it is city or village … how far are the sewage lines from the borewell ? Sometimes the sewage pipes can get cracked due to vibration while drilling . Advisible to check sewage lines and rectify fault . After that borewell cleaning is required