Water Management

i understand this depends on lot of factors like economics, geography, govt etc. But major topics i want to understand on high level are:

1) How many types of water usage are there(domestic, industrial etc)

2) From where water comes(rivers/ rainfall, groundwater) and where it goes back(sea)

3) What kind of water is suitable for domestic, industry needs?

4) What are 90% general proven ways to make best use of water for all kinds of needs(sustainable development)

Thanks

Tarun