It was worse in the drought of 1990. I lived in Ventura then. At one point, residences were restricted to 1200 gallons a month. People along the Ventura/Santa Barbara corridor dyed their lawns green because they couldn't water them. My wife and I used to go stay in a motel once a week just so we could take a nice long shower (no water rationing for commercial businesses). The residential ration in Ventura this year is a little over 6000 gallons a month. That's about 1/2 the average residential water use nationwide. Toilets use 27% of residential water, so go take a leak in your backyard once in awhile (but don't get arrested).
The biggest problem with water in California is that 99% of the rain and snow melt-off runs right out to sea. California's fresh water needs to be trapped. The state needs many new reservoirs and canal systems but that means many big new dams and epic excavation projects. The cost would be epic too. Really epic.
There's a classic book about water politics in the West: Cadillac Desert: The American West and Its Disappearing Water by Marc Reisner. PBS did a great documentary based on the book. Reisner's tome is more relevant today than it was when published in 1993. It deals mainly with California, Colorado, Arizona, and Mexico, but if you live anywhere west of the Mississippi, you probably need to read it.