how can there be wastage of water due to leakage e.g taps, pipes,etc?

Answer 1

one drop every 2 seconds wastes about 100 gal year x the number of leaks

Answer 2

Any water that is not used is considered wasted. This can be from a toilet with a bad flapper. Bad adjustment of the water level in the tank which causes water to go into the overflow pipe. Outside faucets are not used on a daily basis and can drip as can inside faucets. Leakage from rotted pipes and bad joints may only drip but this adds up over time. A water heater with a defective P/T relief valve that has piping exiting the living area of the house can flow unnoticed for long periods of time.

Answer 3

You can proper check taps after using washroom.