Long Beach is urging its residents to cut back on water during this dry season. What troubles me about these calls to ration resources is that it relies on moral persuasion rather than self-interest. For example, no one would every say "cut back on buying iPhones since there aren't enough to satisfy the demand." Instead, the price would simply go up so that those who want it most will have access. Those who don't want it as much will wait until demand subsides.
But when it comes to electricity and water, instead we rely on these moral imperatives. "If you don't cut back, then there won't be enough for everyone." What winds up happening is that those folks who are unfortunate enough to have scruples, a high ethical standard, will heed the warnings and cut back. And those folks who don't give a rip about anyone else as long as they get theirs will go on using just as they always have. At bottom, this kind of rationing is a tax levied only on good citizens, a punishment for caring about your community.
I don't know much about how these utilities are regulated, but I'm guessing that some manner of regulation prevents the utility companies and water districts from simply upping the rates of usage to assuage the demand instead of having to resort to begging.