That’s so strange to me. Living in Australia, we face very similar periodic drought conditions that California faces as well. Rather than being discouraged from capturing rainwater to use, we’re actively encouraged to do so, with many governments previously offering subsidies for rainwater tanks particularly during drought times. We have specific colourings for rainwater taps (purple) and you can buy signs to put up in your yard that say that you use rainwater, so people don’t get mad if you’re watering your lawn. These subsidies were usually alongside heavy water restrictions including not being able to water lawns; not watering plants during daylight hours; not using a hose to wash your car (a pressure washer from a bucket is allowed) etc.