It's summer, and I've been thinking a lot about water these days. I watch the shrinking snow pack on Mt. Hood, and hope that we'll have enough for farmers to irrigate crops this year. I bring a large cup of ice water to work each day, and am grateful that I have access to clean water to drink.

I'm also preparing to speak about my new book, The Great Trouble, which will come out in September, and, as it happens, has a lot to do with water

One day in late August of 1854, in the Golden Square neighborhood of London, a baby named Fanny Lewis fell ill. A few days later, a man on the same street (Broad Street, now Broadwick Street), died from cholera. Warning flags were posted, families who had someplace to go fled, and carts began to pick up the bodies of those who had died.

The following Sunday, September 3, a 41-year old physician named John Snow walked from his home to stand on Broad Street and take some water from the pump to test it. he was about to make medical history, proving that cholera was caused not by miasma, or bad air, but by water.

More than 600 people died in the 1854 epidemic. Eventually the cholera was traced back to seepage into the well from the cesspool where Sarah Lewis had rinsed out her baby's diapers.

John Snow convinced local officials to remove the pump handle on September 8 By then, the epidemic was winding down. Sadly, though, Fanny's father, Thomas, a constable, came down with cholera that day. He died on September 19. Had the pump still be in use during his illness, it's likely more people would have died.

My book is historical fiction. But cholera hasn't disappeared from our world. I hope young readers will come away not just with a better understanding of the past, but an appreciation of the work that still needs to be done to provide clean water to all families.