When I think of "directly", it's not just drinking, but all water usage under your direct control. That includes cooking, cleaning, bathing, flushing, watering your plants, etc. Basically everything that flows through your home. It would not include things like the water used to grow the food you buy, to water the grass in your local golf course, etc.

I'm on the board of a small California water company with ~750 customers. Our average household usage is ~100 gallons per day, a little more in the summer and a little less in the winter. Most households here are 1-2 people, mostly people over 60, and very few children. This is a forested area in the mountains (4,500 foot elevation) with no agriculture. I'm only aware of one lawn and no swimming pools. We get a lot or precipitation, so most plants and trees around here do not get watered. All that to say that we're likely lighter usage than a lot of areas, especially in California. So 100 gallons per person per day being used directly is probably a reasonable order of magnitude guess.