I participated in your recent MMWD water survey and just read the results. I believe I fit the profile of your average responder, with one exception—I think we can hit the 40% reduction goal. I own and live in a 2100 sq foot home in San Anselmo with large established gardens.
During the 2015 drought, like many others, I removed my grass, reworked my drip irrigation system, planted low-water shrubs (I only have one small tree), and installed low-flush toilets. It's just my wife and me, so our indoor needs are modest. Over the last two years, the "historical chart" on my MMWD water bill indicates I use 40% less than the average district customer and 33% less than the average customer in my area (North).
I bought both a Flume water monitor and a Rachio3 smart-controller from MMWD ($430 retail for $135 after rebates) for the current drought and again fine-tuned my drip system. The devices were easy to install and are controlled through my home Wi-Fi using an iPhone or computer. I now water on-demand and receive data instantly, down to the minute.
Without much additional time and effort, I'm tracking to reduce my water usage by another 30-40%. I estimate 95% is coming from more conscientious, efficient outdoor irrigation. The operative word is tracking. Without a Flume/Rachio, I don't think I'd put in the effort, given I'm already one of the "super savers."
You should have asked people if they know how much water they use to irrigate their property. I bet nine out of ten wouldn't know and would be shocked if they did. That's not a criticism. I didn't know until I started using a Flume.
We may not be able to hit a 40% reduction, but we can do better than 20%. I'm using an average of 60 gallons a day on non-irrigation days. On the one day a week that I irrigate following MMWD's weekly watering guidelines, I use an additional 100-120 gallons, and that's with a finely tuned irrigation/drip system. I would have been up around 200+ gallons with my old system and watered twice as often.
They say you can't manage what you can't measure. I think that is very true in this case. That said, thank you for hosting the survey. It's always good to know where the public stands, particularly on big ticket items like water services.