The builder after completing the construction should have handed over the premises to the association which he has not done so far, may be there is o association or society formed by the flat owners by themselves.
The builder cannot escape the liability to provide water which is basic amenity and essential item for survival.
Did you not find the reason that why the water facility was not provided properly?
The builder cannot dodge giving you proper reply to this question.
Why was the property not transferred to your mother's name when you have paid the entire sale consideration amount?
Is the sale deed executed and registered on her name?
Your inaction for the past four years has encouraged the builder to do the wrong things continuously.
You can issue a legal notice and drag him to the consumer court for his deficient services and demand suitable compensation also besides the reliefs and remedy for the current problems.
Consult a local advocate and proceed as per his/her further advise on the issue.