Flint water Detroit.jpg

The difference in quality of water from the Flint River and Detroit was displayed at a news conference in September 2015 in Flint, Michigan.

(Flint Journal file photo)

All eyes are fixed on Flint as the crisis over lead in the city's drinking water supply has unfolded at an accelerating pace since 2014.

But Flint is not the only municipal or private water supply in Michigan where the drinking water is testing at or above levels that researchers and public health officials consider to be the threshold for concerning exposure to a potent neurotoxin.

Michigan Department of Environmental Quality records show that six private water supplies in Michigan and two municipalities -- not including Flint -- meet or exceed the federal limit on lead and copper in water tested at the customer tap.

Another six private and 16 municipal systems across the state, ranging in size from 25 customers to more than 120,000, tested for levels that are below the U.S. federal limit, but above safety benchmarks used by the World Health Organization, the international public health arm of the United Nations, and the Virginia Tech university team that helped blow the whistle in Flint.

Michigan cities with lead at or above the WHO benchmark include Kalamazoo, Muskegon Heights, Benton Harbor, Owosso, Ionia, Marysville and St. Louis.

The statewide lead records underscore a widespread problem with American drinking water infrastructure that, in communities with homes and commercial buildings constructed prior to the mid-1980s, continues to supply vital tap water through private service line connections that leach lead into the liquid.

Database of Michigan public water system lead levels

"I think Flint is the tip of the iceberg," said Yanna Lambrinidou, an assistant science and technology studies professor at Virginia Tech. Lambrinidou, alongside civil engineering professor Marc Edwards, spent years researching the lead contamination that plagued Washington, D.C. between 2001 and 2004 -- a major poisoning that echoes in the Flint crisis more than a decade later.

That iceberg? Millions of lead service pipes that join municipal mains to older homes in cities around the county, but primarily in the eastern U.S. and Midwest.

RELATED: In Flint's wake, nationwide lead water testing methods questioned

The lines are known hazards and many cities stopped using them decades ago. But, exactly how many are still in use is hard to say because, Lambrinidou said, there's never been a systematic effort to document the problem. A recent American Water Works Association survey estimated about 6.5 million. Lambrinidou suggested it could be more than 11 million nationwide. Water utilities were instructed to inventory the lead lines in the early 1990s, but typically those records, if kept, "are shoddy."

As the hole is filled in in the background, an piece of an old lead water pipe sits next to a new copper pipe, Friday, Jan. 22, 2016 at a home on Greencroft in Lansing, Mich. Lansing's municipal utility says it's nearly eliminated lead water service lines since concerns in 2004 prompted it to launch a massive program to replace them with copper lines by 2017.

The information, she said, is "needed desperately."

In Kalamazoo -- the second largest groundwater drinking system in Michigan -- public works staff say that out of 46,000 total service lines, 8,122 lead ones are still used in the system, which serves the city and, like many larger municipal water systems, several surrounding suburban communities.

The city treats the water with anti-corrosion chemicals -- a step missed in Flint when that city switched its water source. To control for corrosion, Kalamazoo adds sodium hexametaphosphate, which helps create an insoluble coating on the inside of pipes that cuts down on the amount of lead leaching into the water.

Kalamazoo replaces lead service lines during street restoration projects, repairs to service line breaks and whenever targeted sampling indicates lead and/or copper in the city's water supply exceeds 15 parts-per-billion (ppb) -- the U.S. Environmental Protection Agency regulatory limit for lead in drinking water.

It's worth nothing that 15 ppb is a regulatory measure and public health agencies and advocates consider that generous. The World Health Organization says that, while no level of lead is safe to drink, 10 ppb is guideline level for action. Virginia Tech researchers consider 5 ppb a "cause for concern."

In 2014, Kalamazoo tested at 13 ppb. In 2013, the city of Caseville in Huron County also tested at 13 ppb, according to the most recent DEQ records.

Not including Flint, the highest recent municipal water levels were in the Manistee County village of Bear Lake and in the Upper Peninsula's Crystal Falls Township. Both tested at 15 ppb; Crystal Falls in 2013 and Bear Lake in 2015.

What do those results mean? Well, it's complicated.

MORE: Full coverage of the Flint water crisis

The results do not mean every person drinking water from those systems is swallowing lead at 15 ppb with each gulp. The benchmark is derived from sampling a pre-determined number of homes already known or suspected to have leaded water problems and calculating a statistical distribution of the lead content in the water systems based on those samples.

Utilities and regulators call it the "90th Percentile" test -- meaning 90 percent of tested homes must test below 15 ppb before the EPA requires the utility to begin taking measures to fix the problem. The goal is to ensure no more than 10 percent of the population is drinking water with lead above the 15 ppb threshold.

Even some water utility managers think that's a bit convoluted.

"The only rule I've seen written this way is for lead and copper," said Bari Wrubel, water plant supervisor in Marysville, which tested at 12 ppb in 2014.

Water plants have hard line benchmarks for turbidity, alkalinity, bacteria levels, fluoride, chlorine and other additives or contaminants. Those testing samples are generally taken by utility staff at the plant. But with lead and copper, the samples are collected at home by the customer, usually in the morning, using instructions and a sample collection bottle provided by the utility.

The results depend greatly on the customer following the sampling directions properly. Virginia Tech researchers say there's a great potential for data distortion if the sample doesn't catch water that sat overnight in the service line.

"You have to count on it being done correctly," said Wrubel, who said testing targets older homes and the results are not indicative of the whole system.

In Marysville, the 12 ppb result was based on data from 30 homes. In Kalamazoo, the 13 ppb result was based on 59 sampled homes.

Sue Foune, director of Kalamazoo's public services department, which includes the water system, said three homes tested at or above the 15 ppb action level. Those had lead service lines that were subsequently replaced. Three homes tested between 9 ppb and 4 ppb, and the remaining 53 homes tested less than 3 ppb, which, in utility parlance, is a "non-detect."

Sue Foune, water plant manager in Kalamazoo, checks bacteria samples in this 2008 file photo.

Of the 15 ppb samples, the first came from an outside hose. Another came from a basement utility sink that contained a lead solder. The third was from a vacant house. The homes were all "Tier 1," or locations with lead service lines.

"We follow the EPA and state protocol," said Foune. "We believe we're fine."

Bear Lake officials did not return a message seeking comment. The DEQ and EPA have not taken action there or in Crystal Falls Township because the limits do not exceed 15 ppb.

Thomas Lesandrini, Crystal Falls Township supervisor, said the rural water system is lead sampling again in September after the 2013 test showed concerning levels of lead in some homes with lead in their plumbing.

"We have a lot of older homes up here that seem to be the problem."

As for the private water systems on the list, the highest contamination in the DEQ records is at Chateaux Du Lac Condominiums, a homeowners association in Fenton that tested at 79 ppb in December 2014; and the AuSable Valley Community nursing home in Fairview, which tested at 68 ppb in December 2015.

The Fenton condos get water from a private well, say managers.

"It seems high," said Mark Piper, president of Piper Management. "We do acknowledge the DEQ said there was a lead issue and we do have a corrosion control plan in place with them and we're implementing it as we speak."

In Fairview, Wellspring Lutheran Services administrator Michael Stephenson acknowledged an "anomaly" in its senior care facility private well water, and, in an email, said the facility has "replaced some fixtures and equipment."

Wellspring is working with consultants to develop long-range testing protocols, and has "informed its residents regarding what was found, what has been done to address it, and what will be done moving forward."

Database of Michigan private water system lead levels

Garret Ellison covers business, environment & the Great Lakes for MLive Media Group. Email him at gellison@mlive.com or follow on Twitter & Instagram