Water withdrawing from water tank

If you know who steals water from your water tankl, you talk to him or issue a legal notioce, failing to listen or refrain from doing so, you can take legal action against him by lodging a complaint with the police or local civic body or file a suit for injunction against him.

File complaint in Municipal authority of your zone against suspected water thief. 

@ T. Kalaiselvan, Advocate @ R.K Nanda, 

Sir, first of all thanks for giving your precious time, to my post,  I can't say anything wrong to the owners having roof right even after knowing water has been taken by them not by neighbours, before starting legal course through Civic body, police or court, first I want to ensure whether I have a right to have a water tank on roof or not when no roof right has been given through sale deed. Seller (lady) had full ownership of building later sold lower 3 floors and 4th & 5th floors are holding by her next generation with roof right. Rgds

In a apartment complex like this, even though the land owner has terrace rights she cannot refuse to install overhead water tank on the terrace because it comes under basic amenities.

As a matter of fact the terrace is supposed to be a common area insofar as installation of overhead water tank to the other floor owners.

Is it a building with one flat on each floor?    What do you mean by roof?  Is it terrace? I presume that the water tanks are on the terrace. Is there a separate tank for each flat?  In a building with apartments the terrace will be common area. It cannot be owned or sold to a particular member. If you have a separate water tank there will be exclusive connection to your flat only. Others will not be able to draw water from your tank. If there is a common water tank with connection to several flats, each will withdraw water according to his requirement and if the supply is not sufficient the tank will become empty. It is not possible to put blame on one person. If you have a common tank and common vertical pipeline, you on the lower floor will be at an advantage over the upper floor members. If the upper floor member is drawing water and you open your tap at the same time, the water supply to the upper floor will get reduced. What is the size of the vertical line, is it 1/2", 3/4" or more? Generally each tap will have a 1/2" connection. If the entire vertical line is 1/2", water supply to the 4th floor will stop if you open the line.

Thanks to all learned persons for sharing your precious time & energy, my problem has been solved & my seperate water tank has not only been shifted on floor of terrace but connection of water pipe line has also been completed, it was actually not due to cooperation, actually there was illegal construction too on terrace, any advancement in issue could damage illegal construction which paying that person. Thanks again.

To my understanding, you are entitled to keep your storage tank in the terrace even if you have no terrace rights.