Alerted by recent tremors, Folks in Potosi, MO, wondered what they would drink if an earthquake or tornado destroyed their bridges, damaged municipal water systems, and left the community isolated. Since Washington County is a land of spring-fed waters, it seemed clear-running streams were a good bet. But with water, what you see is not always what you get.

Mayor T. R. Dudley wondered whether to apply for a grant to get five systems for emergency backup. That’s why EDGE OUTREACH-St. Louis went to Potosi. Civic leaders wanted to field test a McGuire system first.

The weekend before the live demonstration, Dave Westrich and Neal Powers tested two possible water sources: a fishing pond in the municipal park called Bilderback Lake; and a clear spring-fed stream running though the center of town. All the smart money was on spring water. That sample turned black within nineteen hours. The sample from Bilderback Lake turned black too, but it took twice as long. It had to be a mistake, right?

No. On August 5-7, 2011, Neal and Dave, along with Earlene Doyle and Jim Keagy, repeated the tests with the same results. The clear stream running through the park, the one filled with splashing kids, was dangerously contaminated with bacteria. Meanwhile, over at Bilderback Lake, we chlorinated and safely drank the algae-laden water.

After hours of puzzlement, we realized the windmill on the opposite bank of the lake was not pumping water out. It was pumping air through the water. Aeration works for the same reason hydrogen peroxide cleans a wound. Bacteria and germs die when exposed to oxygen.

Our experience in Potosi confirms what we tell students in water purification courses. You can’t judge water by its appearance. Test it. Test it. Test it. Mayor Dudley applied for the grant. And we have entered a new dialog with first responders.