It depends on where the water is, and an awful lot of it is in the sea and deep in the earth's crust
Supplies of fresh water suitable for human and animal consumption is much more limited and distribution can be patchy. Think of Australia and the long term drought that has contributed to its wildfire problems and is slowly killing its cattle rearing industry. Similarly if too many people live in one area demand soon exceeds supply and has to be brought long distances at great cost
In the 1980s and 90s, in a long dry period, many of my local chalkland streams ran dry because so much water was being taken from underground resources to supply homes, farms and industry that there was none for the streams.
Getting sufficient fresh potable water to all those demanding it can only be done by building huge reservoirs.My village, no parish, in Oxfordshire is threatened by one bigger than Kielder Water surrounded by an 80 foot dam, or a sit is known in this kind of case - a bund -
The alternative is desalination and piplines taking water hundreds of miles across country. Desalination is very expensive. OK if you are a middle eastern sheikh and it is the only source of water available, but in this country it could double our water bills.
That is why we save on water