Drainage water into our property

Respceted sir, my name is gurunath and my concern is my neighbors waste water from bathroom and rain water enter into my property. we built compound wall and the our toilet is attached to it. the water comes from under my toilet and enters into the passage in front of it .whole passage becomes wet whenever they wash dish or wash clothes but water does not look entering into my property externally but wetness is visible on the floor and the concrete also become weak and it is peeling off. they dont have any public gutter or pipeline to send water out after repeated request they built 3-4 feet deep hole in the ground and built 4inch wall but they didnt diverted water away from our compound wall hence water still coming into our property. i am thinking of putting a damage suit against them. 1-can i apply for damage suit. 2-what precautions should i take before filing the case. 3-how can i prove the water is coming from their usage and not by me. 4-how much damage money i can ask. 5-should i repair it before putting case or after filing the suit. 6-what if during heavy rain the compound wall and toilet fall or causes damage to me . can i still file for damage suit as the compound wall and toilet were already become weak due to continues water input. 7-or shall i wait and watch til wall and toilet fall. 8-if i ask to local lawyer. what should i ask. ask for damage or just to complain to police? please i am in need of your valuable suggestions. thank you.