That is talking about the water you use in your household. But that is a tiny faction of all water used in total. Industry and farming absolutely dwarf household consumption.
A ton of water is used to grow Alfafia. There is no way it's profitable if you had to desalinate it first.
More realistically, California stops growing alfalfa and stops raising beef cattle altogether. That would free up enough water to water every lawn across the state.
I was just looking into a fake lawn for my next house, but you don't recoup the cost for 7 years. The builder has been putting in smaller lawns in the front, so we'll likely put a small one back and be smart about watering it (not in the middle of the day, properly position sprinklers etc.). Or we'll xeriscape it
A ton of water is used to grow Alfafia. There is no way it's profitable if you had to desalinate it first.