[MindSpunk]

While I'm not saying waste when things are plentiful in general is okay, I think water is a unique case that can be treated differently.

Comparing to energy costs isn't the same because using the energy for the incandescent bulb consumes that energy permanently. The gas/coal/fuel can't be un-burned. Although solar changes this as the marginal cost of that energy is free.

Comparing to food is similar. Once the food is wasted it is gone.

Water is typically not destroyed, it's just moved around in the water cycle. Water consumption in a region is dictated by the throughput the water cycle replenishes the reservoirs you're pulling from. "Waste" with water is highly geographic, and it's pretty reasonable to take exception to California projecting their problems to geographic regions that they aren't important.

[fennecfoxy]

It still takes energy, chemicals and therefore pollution to clean water once it's been turned into greywater.

[ignaloidas]

Sun is continuously running a very nice distillation cycle the size of the world that makes fairly clean water just fall out of the sky. It's only a question of where does it fall, and how much. If you want it even cleaner, wait a couple centuries for it to filter down underground, and get it from there - besides maybe a bit high mineral contents, that can easily be removed, it's essentially free, clean water. The only question is how much it's replenished in the area you're taking it from.

There's plenty of areas where there's more rainfall, than there is outflow/evaporation, with water continuously replenishing deep groundwater. "Saving water" in such areas is of little concern besides the basic, economic one of well maintenance - each one can only pull so much, and more usage means more wells, and more upkeep.