Ours is a registered Association (Societies Act)  and we are collecting the maintenance charges equally irrespective of the fact whether it is a two or three bed room flat or of the UDS area. 
This decision is taken in our G.B. Meeting because of the fact that the maintenance is collected for keeping the Security personnel, cleaning and lighting the common area, purchase of water when yield from bore wells are not sufficient and pumping water from bore well to sump and from sump to OH tank. 
We are providing 24 hours uninterrupted water supply. We wish to know whether any mention is made in the act regarding collection of maintenance charges.

The Act only refers to payment of maintenance charges on the basis of percentage of undivided share in common areas and facilities. 
However, in many instances, the maintenance charges are being levied on the basis of number of units owned irrespective of the size.  This is only a convenient arrangement which is to be treated as having been accepted by the parties concerned.