An official timeline of the water contamination results and subsequent boil order imposed by Deerfield.
Thursday, Aug. 8
Water samples taken at five locations, including the Hawthorne Lane and Pine Street sites.
Friday, Aug. 9
The Highland Park lab informed Deerfield that the Hawthorne Lane site showed a "presumptive positive" for bacterial growth. It was also reported that the Pine Street site sample had signs of bacterial growth, but that it was "atypical" and did not warrant concern. Because of the presumptive positive, more samples were taken at and around the Hawthorne Lane site.
Saturday, Aug. 10
The lab informed Deerfield of a presumptive positive for total coliform – not fecal coliform – from one of the samples taken Friday. Additional tests were ordered. Meanwhile, the official results from the Aug. 8 samples were available – and tested positive for fecal coliform – but that information was not fully communicated. No boil order was issued.
Sunday, Aug. 11
All samples taken Aug. 10 came back clear of bacteria. But Aug. 9 samples were confirmed as positive – but not identified as total coliform. Because of that breakdown in communication, no boil order was issued.
Monday, Aug. 12
The Highland Park lab reported that the Aug. 8 samples taken at Pine Street and Hawthorne Lane were positive for fecal coliform. IEPA instructed Deerfield to issue a boil order 10:45 a.m.
Tuesday, Aug. 13
Samples taken Aug. 12 came back clear. Ten more samples were taken.
Wednesday, Aug. 14
Samples came back clear. Boil order was lifted at 11:20 a.m.