alt Hacker NewsThe short answer is all those problems have already been solved.
Israel desalinates 75-85% of its drinking water. The problem is political and economic dysfunction.
California for example could be doing widespread desalination with nuclear power and technology from the 1970s. They could also greatly expand reservoirs and waterways, but don’t do it. Very similar to Rome in the 400s, when people were using aqueducts built by a past civilization but lost the ability to construct them.
Nuclear is very expensive per MWh and thus per litre of water generated
Solar on the other hand is very cheap, and you don't need to desalinate 24/7 -- just do it when power is cheapest (which is during the sunny times if you have large amounts of solar, during windy if you have large amounts of wind, etc)