You can adhere to the following steps for addressing the seepage issue and claiming damages:-
i. Issue a legal notice to the flat owner above you, highlighting the problem and demanding corrective action. This can be done under the provisions of the Consumer Protection Act, 2019, seeking compensation for the damage caused to your property due to their negligence.
ii. If the owner fails to respond or refuses to cooperate, you can file a complaint with the Local Consumer Court or the Real Estate Regulatory Authority (RERA). The court could direct the owner to rectify the seepage issue and compensate you for the damages incurred.
iii. You can also rely on the principles of tort law, specifically the principle of ‘nuisance’. The leading case of MC Mehta vs. Union of India established the concept of absolute liability for harm caused due to hazardous activities.
iv. Document all the damage caused, gather evidence (such as photographs, receipts of repairs, etc.) and seek legal counsel to navigate the intricacies of the legal process efficiently.