Question

though water can be regarded as renewable resource we are told not to waste drinking water . why ?

Answer 1

Water can be renewable resource, but it takes a lot of time and money to renew it. 99.99 percent of water rests in the ocean, and it is unfit for us, and that leaves nearly 0.1 percent for +900 million people. If we start wasting it on extremes, we would last a day, and thus, the best option we have is to preserve it.