Bangalore Water Supply & Sewerage Board [Bwssb] — wrong water bill and usage details

Address: 4th Cross Road, Jogappa Layout, Veerannapalya, 560045

We have rented a flat in december in jogappa layout in veerannapalya.in the month of may, we received water bill of ₹24000. We have been not been using kaveri water. We checked the water bill online every month and it says every month the gate was locked. We got the first reading as 200000 litres and usage as 22000 litres. I just have one doubt, when they took the 1st reading, how they decided the usage. And according to the bill, the next month reading was 450000 litres. And i have just one confusion how come few people who are mostly at office would have used 250000 litres even when we were not using supply water. And again next month's reading was 650000 litres which just sounds impossible.