A Tribune analysis of the results shows lead was found in water drawn from nearly 70 percent of the 2,797 homes tested during the past two years.
But in one of five Chicago homes tested since January 2016, the Tribune analysis found, samples contained high levels of lead after water had been running for three minutes.
By contrast, the newspaper’s analysis of the more recent testing kit results revealed that lead-contaminated water was found in at least one home in all 77 Chicago community areas.
At more than 100 homes across the city where lead levels reached 15 ppb to 270 ppb in testing kit samples, water department officials conducted follow-up testing that involved drawing 10 consecutive 1-liter samples.
Nearly all of those samples contained more than 5 ppb of lead, the Tribune analysis found, with levels generally increasing rather than decreasing as more water flowed out of the taps.
At Abrahamian’s Northwest Side bungalow, the first sample of unfiltered water collected by the department had significantly lower levels of lead than the amount in her own sample — 7.6 ppb, compared with 250 ppb.
An additional sample collected after the water had been running another three minutes contained 24.8 ppb of lead — nearly five times higher than the FDA limit for bottled water.
Milwaukee has estimated that digging up and replacing all of the city’s lead service lines would cost $750 million.
Since Emanuel took office in 2011, Chicago has borrowed more than $481 million for water projects, including $312 million to install new water mains.
Chicago residents interested in having their tap water tested for lead can order a free testing kit from the city at www.chicagowaterquality.org.