Delhi Jal Board — water bill issue

Address:

New Delhi, Delhi, 110062

I reside at delhi south zone khanpur extension tigri colony and the concern is related to water bill, since delhi government has given the of 20000 liters of water a month would be supplied free to every household. If this limit gets above then nominal charges will be applicable. My question is we are three members in my family then how much water we may consume on daily basis, i believe very less which comes under 15000 liters per month, then how come my bill keep getting increase since last few months and now its rs 19267 which is unimaginable. Please have a look on this since i am not supposed to pay such an amount where government has already given the free water supply to delhi citizens