There are five new popular books on water this year

The two I will recommend are:

Steven Solomon, Water: The Epic Struggle for Wealth, Power, and Civilization.  It offers a very good history of water technologies, here is one good review.

David Zetland, The End of Abundance: Economic Solutions to Water Scarcity.  Of the five books, this one has the most policy truth.  Also, David reviews one of the other books.