Chicago to Test Ozonization
to Cut Down on Chlorine

June 21, 1999


Chicago is testing ozonization as a water treatment process that may improve taste, remove odor and cut down on chlorine, city Water Commissioner Judy Rice said Sunday.

For a year the city will study the new process which involves passing water through ozone, a form of oxygen.

Chicago is investigating the new technology partly because of the zebra mussel. As zebra mussels filter their food from the lake, more sunlight penetrates through water, creating algae growth that can make drinking water taste mossy.

Ozonization could improve water taste by fighting that algae growth. It could also lessen the amount of chlorine used to purify city water.

Ongoing studies are investigating potential health effects of drinking chlorinated water and the disinfection byproducts that are created when chlorine reacts to compounds in the water, Rice said. Questions have been raised on possible health risks, such as cancer and miscarriage, Rice said.

Chlorine cuts down on waterborne sicknesses that stalked early Chicagoans. "Before the turn of the century, people had their cholera outbreaks, their illnesses that came about because they were drinking water that hadn't been treated with chlorine," Rice said.

"Currently chlorine is a necessity for safe drinking water in terms of preventing illness related to bacteria and viruses, and has been for the last hundred years," she said.

Ozonization would disinfect water of organisms such as cryptosporidium, which sickened 400,000 Milwaukee area residents in 1993. It contributed to the deaths of an estimated 100 people.

The process is already in use in Milwaukee, central Lake County and Los Angeles, Rice said.

The new technology would cost the city about $80 million at each of its treatment facilities, including the Jardine Filtration Plant at 1000 E. Ohio and the South Plant at 79th Street and the lakefront, Rice said.

The city is planning a demonstration of the process Thursday. Eventually a "taste panel" of water department employees will check the treated water for improved taste.