For any of you who are chemistry geeks like me, I found the conversation at a public hearing Monday night on the proposed filtration system for troublesome Well 29 on the city's east side very interesting.

Basically, what's happening right now is this:

Manganese and iron from the soil are getting into the water in their reduced form as ions -- soluble, electrically charged forms of elements. Elements generally are not too happy when they are ionized, so the manganese and iron have been reacting with the chlorine added to water for antibacterial purposes to create manganese dioxide and ferric hydroxide, two solid compounds (the former, gray and the latter, red-orange) appearing in the water distribution system. The compounds accumulate on pipes and if not flushed out before a water emergency (like a fire), get into people's homes and cause their water to look, as one resident complained, like "light beer" (although I suppose it could have been worse -- he could have said it looked like an amber or stout).

The two substances are not harmful to ingest (in fact, if you look at any multivitamin, you'll likely see iron and manganese on the label), but residents in the area have been plagued by other problems from the water including stained laundry and the perception that their water is dirty and/or unhealthy. The aesthetic standard for manganese in water is 50 parts per billion, while the lifetime health standard (meaning you would have to drink the water for a lifetime to experience health problems) is 300 parts per billion.

Well 29 is currently at around 180 parts per billion, causing significant aesthetic problems, but city officials at the meeting assured residents that light beer will no longer be "on tap" from their water faucet, as construction on a filtration system for these two substances will begin probably by September of this year, and it will be completed by about June of next year. The filtration system adds a little extra chlorine to make sure there is enough in the water after some gets used up in creating these two compounds, and essentially filters out all of the iron and more than 90 percent of the manganese, reducing it to 20 or less parts per billion. The manganese is harder to filter because the reaction between manganese and chlorine happens more slowly, but the filter will be made out of a material called pyrolusite (essentially manganese dioxide -- the compound itself speeds up its own reaction, another interesting bit of chemistry), which will speed up the reaction and hopefully reduce manganese to 10 parts per billion.

By next summer, Water Utility engineer Alan Larson said some of the best water in the city will be coming from Well 29. Well 29 will begin by operating at half-power (1,100 gallons per minute), which is much more than its current operations on stand-by status, and it will relieve some pressure on other wells in the fast-growing east side. For residents with more minor manganese and iron problems, such as wells 7 and 8 on the near north and east sides, water officials say a similar filtration system is possible in future years. Another possible site for filtration is Well 10, which is located on the near west side, but hasn't operated since 2006 because of manganese issues.