Look at your water bill and find out what the minimum rate is for municipal water in your area. Does the rate increase as the use of water increases? Why do you think the government charges a higher rate for greater use of water?

The minimum rate of municipal water in my area is 300 rupees per month.

Yes, the rate of the water increases as the use of water rises.

The government increases the rate of water as water is a resource which needs to be conserved and when the prices of water will be higher than people will use water more sincerely and hence it would decrease the wastage of water.