Neighbour-Well-Distance

I am living in Kerala. and have less than 5 cents.  I have purchased my said property after my neighbour. My neighbours well is  4 feet from our common boundary.

mean while i am in need to dig one new pit to dump drainage water. What is the distance I should maintain from  or rather i will say how much minimum distance i should leave from our common boundary.

expecting help , immediately.

regards

johnes