You are not liable to rectify any leakages on top floor of flat after period of 7 years 

2) The defect liability period, as per RERA, is typically five years from the date of possession

Dear Sir/Madam,

You are suggested to go through the terms and conditions of development agreement, if any because the terms of repair/guarantee/warranty might be mentioned in this. If the liability lies with you, you may repair the said seepage. if the same is not given in any document i.e. Sale Deed, Development agreement, etc.; then by virtue of experience you may tell as to how much time should be given as warranty for damages. Also, try to find out the reaons of seepage. If due to any reason, the liabilites falls under your court, you must proceed for repair. If the liability does not fall for you, you may deny for repair. Alternatively, as a goodwill gesture and maintaining further better relations, you may go for repair with shared cost between you and the concerned consumer.  

Since the flat was handed over in May 2018, and it’s now over 7 years, your liability under the builder warranty (typically 5 years under RERA or contract law) has expired.

As a result:

• You are not legally bound to carry out free rectification now.

• Seepage after 7 years is typically considered a maintenance or wear-and-tear issue, now under the society’s or owner's responsibility.

• Since the society is unregistered, there's no formal structure to handle repairs, which complicates it—but still doesn’t make you liable unless there’s evidence of structural defect intentionally concealed.

Recommendation: Politely inform the owner that your legal liability period is over, and suggest they raise it with the society or hire professionals for waterproofing.

Let me know if you need a drafted response to send to the customer.

In India, a builder is typically responsible for rectifying structural defects or issues with workmanship in a flat for five years from the date of possession, as per the Real Estate (Regulation and Development) Act, 2016 (RERA). This is often referred to as the Defect Liability Period or the builder's warranty. After the five-year period, the builder's liability for structural defects may diminish or be extinguished, depending on the specific terms of the agreement and relevant laws. 

- Under the Real Estate (Regulation and Development) Act, builders are under obligation to rectify structural defects within 5 years of handing over possession of the flat to the buyer. 

- Further, a buyer can claim rectification of defects within this 5-year period from the date of getting the physical possession 

- Since, 7 years already passed then you are not responsible for the same. 

Builders are liable to do the needful upto 5 years form date of I possession as per rera. In your case the society needs to take care along with both the owners of the flat