We must pay for the maintenance of the leaking water pipe.

This is not complicated, clear thinking!

First, you have to define whether this is a private part or a public part.

The proprietary part shall be the responsibility of the developer within the warranty period and the owner shall bear it outside the warranty period.

For public parts, the developer is responsible for the warranty period, and the property management company is responsible for the warranty period (if it is a minor repair, if it is a medium repair, update or transformation), which requires the maintenance funds of the owner.

There is absolutely nothing to worry about. If they don't do this, they must be passing the buck.