> Build a pool.

How does this work without water?

The Earth has a functionally infinite amount of water. If it's dirty, clean it.

That's not how it works. Transporting water from a different location will be an extra cost. Cleaning will be an extra cost. And cleaning is also not perfect. Those who will need water, are usually not those who can afford all this. So at the end you are just moving the problems to someone else, out of greed and ignorance.

Not a problem. Countries should get rich first, then they can afford all of those costs and have money to spare.

We've been building canals for thousands of years.

California has droughts, but never water shortages.

Depends on the usage. According to news, there were water shortages in the past in California. Though, we are not talking just about California here.

The only shortages are for farmers, and a few isolated and very poor towns.

IMO, the (existing) towns should get more state support to have affordable safe domestic water. The shortage is not raw untreated water, but just transporting it and treating it.

The farmers? I sympathize, but they are trying to grow crops in an extremely fertile but arid valley. It's going to be constrained by the natural environment.

Municipal water usage in California is only 20% of all water usage. The rest is almost entirely agriculture, and all that agriculture uses a strange system of water rights where you do not have to reduce consumption during a drought, and the last person in line instead absorbs all the drought problems.

This creates an insane political environment where the rich as fuck agribusiness which owns that final water right is incentivized to get that tiny municipal water usage reduced as much as possible to squeeze out a tiny bit more water for their own business, rather than reform the dumb water rights system which would ensure that they only shoulder a tiny tiny portion of drought scarcity but probably force them to pay a little bit for irrigation improvements or stop growing almonds as cheaply.

The only reason the rest of the country even knows about the California water situation is because those bottom rung agribusinesses are still wealthy as all fuck and have actively paid for national political campaigns

Most municipalities get their water out of the same system, it's just they need so much less so they get by. Also, of the 20% that used by urban water systems, 50% is for outdoor irrigation.

The definitive book on the subject is "Cadillac Desert"