Detroit found more lead in drinking water samples this summer than it has in recent years, and there’s a few reasons to account for the uptick.
Unofficial results posted this month by the Detroit Water and Sewerage Department show Detroit’s water is safe to drink by federal standards.
Still, the number of homes with lead detected in water, the percentage of samples with measurable lead and the maximum lead detected were all up over testing in 2008, 2011, and 2014.
There are three main reasons why:
- Detroit tested more homes (87 this year compared to 54 and 58 in recent years)
- Detroit tested more homes with confirmed lead service lines (71 this year)
- Detroit stopped instructing residents to “preflush.” It’s a common but controversial testing practice once backed by the state that water systems have been instructed to stop using.
Of the 87 homes Detroit tested in the summer of 2016, results show 37% of those homes had measurable lead in water samples. A measurable level is 2 parts per billion or more. In 2014, only 14% of homes tested had measurable lead levels, 17% in 2011, and 24% in 2008.
“That wasn’t a surprise to us but it’s still way, way, way below any figure that would cause alarm,” said Gary Brown, director of Detroit’s Water and Sewerage Department.
The highest individual lead result was 11.9 parts per billion. The federal "action level" is 15ppb.
According to the city, the 90th percentile for lead in water is 4.5 parts per billion. A 90th percentile calculation above 15 ppb, like Flint's, is considered not safe to drink.
Michigan’s Department of Environmental Quality calculates the official 90th percentile. It’s not clear yet how long that’ll take.
“I’m extremely comfortable as director of DWSD that we have some of the safest drinking water in the world. And so I just want to assure Detroiters that we are taking this very seriously and taking every step possible to ensure that Detroit’s water is safe,” Brown said.
Detroit’s top health officer, Dr. Abdul El-Sayed says he’s happy DWSD tested this summer, a year before the city was required to.
“We really, really are trying to kick the tires and really rigorously test the water. The good news is that the testing comes well below the established levels,” he said, praising DWSD for being proactive.
“The levels have increased, but that’s predictable given that we’re taking more samples and those samples are not flushed samples,” he said.
Brown says the city will conduct compliance sampling next summer as well.
Both Brown and El-Sayed say the city plans to embark on a public awareness campaign to assure the public of the water’s safety and to inform residents about what they can do to protect themselves and their family from lead exposure in water.
Detroit estimates it has roughly 100,000 lead service lines in the ground; more than any other city in Michigan. But that estimate is based on the year a home was built, which is not always a correct assumption.