Builder's full power backup claims are pure marketing — fight me

Budget finalised, loan pre-approved — now stuck on which sector. Kids have moved out, so don't need a huge place. Looking at Saini Bhawan, but curious about their power backup. Builders promise full flat backup, but often it's just common areas. How to verify actual wiring and capacity during site visits? Also, water supply reliability, especially in summers, is a big concern. Koi tips hain kya?