In my apartment building located at 18, Central Avenue, Nagpur, Maharashtra, India we have a "dug well" as the common water source. The well in question was dug 45 years back. The well water is being used for potable purposes, some people use it directly for drinking while still others prefer to use a purification technology of their choice.
In order to ensure the cleanliness of the water & well yearly we mix potassium permanganate (10 gm mixed with one litre water and then mixed in well) or lime stone (mixed in one litre water and then mixed in well water).

My question is :

What is the best way / chemical to be used to keep open dug water well water clean and healthy for household and daily usage? What quantity? Frequency of usage?  As of today we are all using the well with layman's knowledge of water quality and purification. I would like to get educated on the same and help in the proper use of this resource.

Jaspal arora
9422148400
jtarora@yahoo.com
Nagpur