It's a thin book, and I have some issues with the authorial tone. Some of the stories are amazing.
But here, on p 29, Jordan Fisher Smith is explaining about storm waters over Christmas 1955:
"But before it was even finished, a huge storm over Christmas 1955 filled Folsom's million-acre-foot reservoir in a single week. (An acre-foot is just what it sounds like, the amount of water it would take to cover an acre of land with a foot of water if nothing soaked in, or just over 326,000 gallons of water. This is roughly the amount an American family uses in a year.)"
First, a little background. I live on a sewer, but the intersecting streets to either side of me are not on the sewer (nor is the long block that connects them). The people who live in that area asked a lot about extensions to the town sewer when it was first created, so an early extension of service was planned to go in. However, others who lived in that area were extremely opposed and, er, dissent ensued. When the Sewer Department put together three meetings to provide historical background on the sewer, as part of information for the current board of selectmen to write a bylaw, these meetings were recorded, and a friend of mine (on the anti-sewer team) sent around the links. I actually had the time and used it to watch the meetings, which a lot more fun than it probably sounds (hey, my neighborhood got compared to the Hatfields and McCoys. I love local politics. Sometimes).
Anyway. _Because_ I watched those in the last few months, I knew that a typical family in my town uses around 160 gallons/day. 160 * 365 = 58,400. But you know, maybe _MY TOWN_ is better than the average American town and more frugal with water. But Boston averages 180/day (65,700). You can find estimates ranging up to 255/day (93,075) or even 400 gallons/day: 146,000.
You'll notice that even the outrageously 2.5x number is producing an annual water use less than _half_ what Jordan Fisher Smith casually mentioned. An American family would have to be going through twice again, to be what this author mentions.
Perhaps the "average american family" in Jordan Fisher Smith's numbers waters the lawn. A lot. My figures may be indoor only. If you watered the lawn at the rate of 10 gallons a minutes for an hour and fifteen minutes every single day of the entire year, well, you'd flood your basement and your lawn would die, but you might come up with the annual water usage he refers to.