It would have been better if you had given this as a new post rather than give under an old existing post.
Ceiling leakage issue:
How many floors has your building. On which floor are you residing? Is it the top floor? Where is the leakage? Is it over the bath-room, toilet or kitchen? If so, is it from the upper floor? The procedure for your complaint would depend on your answer to your question. In any case first write to the Secretary of the Society and obtain an acknowledgement. If you do not get a reasonable response within reasonable time, you write to the Registrar of the Ward in which your Society is situated. Normally the Registrar will forward copy of your letter to the Secretary and seek his reply. The Secretary is required to reply and the Registrar will forward his reply to you. If ,with that if your problem is solved, congratulate yourself. Otherwise you will have to doggedly follow it with letters and by meeting the Registrar.
Storage Tank::
You say the matter was discussed at the AGM. Was it discussed as an agenda item or under "any other matter". If it was under the latter, you cannot expect much. The right procedure would be that the Managing Committee should invite quotations for the project and make an estimate of the expenditure. If the amount is more than Rs.25000/- they should call an EGM ir wait for the AGM, place before them the estimate and also confirm to the General Body that funds are available. If sufficient funds are not available the General Body will have to approve collection of additional funds from members. The General Body should pass resolutions approving expenditure on the project,, and for collection of additional from members duly proposed and seconded.
I can advise you further only after getting more details. I have posted this advice assuming that your Society is in Maharashtra.