A new study by USA Today shows that millions of people in the United States are living in smaller communities that do not regularly test for lead contamination in their water supplies. About 100,000 people are served by water systems that were found to have unsafe levels of lead, but where authorities failed to treat the water in order to remove it.

Journalists reviewed Environmental Protection Agency (EPA) records and visited communities across the United States.

The report further underscores pervasive and widespread lead contamination of water supplies across the United States, despite formal EPA rules mandating testing and lead abatement measures.

These latest revelations come in the wake of the lead-in-water crisis in Flint, Michigan where more than 100,000 residents were exposed to lead-tainted water after city officials switched the city’s water supply from the Detroit water system to the Flint River in order to cuts costs.

According to USA Today, some four million US residents live in communities where authorities failed to conduct mandated lead testing or did the testing improperly. In 2,000 communities lead testing was skipped more than once. Several hundred did not conduct lead tests for five or more years.

The report noted that small water systems were likely to escape close monitoring by the EPA. US regulations exempt small, poorly-funded water systems from stringent water testing requirements. Instead of providing federal resources to help these struggling communities, often in rural areas such as Appalachia, residents are left to fend for themselves.

The results are many times tragic, with residents, including particularly susceptible children, exposed to dangerous levels of lead that can stunt growth, cause permanent mental impairment and lead to other health issues.

There are about 850 local water systems with a documented history of lead contamination where there has been no proper lead testing since 2010.

The USA Today report cited the example of the community of Coal Mountain, West Virginia where the water treatment process consists of occasionally pouring bleach into the old wellhead that serves as a water supply for residents.

State officials labeled 12 water systems in West Virginia “orphans,” because it was not clear who was in charge, and warning letters were ignored year after year.

In Ranger, Texas the family of a two-year-old boy found that their son had elevated lead levels in his blood. They learned later from USA Today that their tap water had lead levels 28 times the federal limit. This all happened while city officials were aware of the lead-in-water problem in their community, but took no corrective action nor alerted residents.

The requirements to run a small water system are often extremely low. For example, the state of Texas requires only a high school diploma or GED and a training course in basic water operation. “You might have to get more training to run a hot dog stand than a small water system,” Paul Schwarz with the Campaign for Lead Free Water told USA Today.

About 350 of the water systems cited by the USA Today report serve schools or day care centers. At an elementary school in Ithaca, New York one sample tested was 5,000 parts per billion (ppb), the EPA threshold for hazardous waste. Investigators found 600 water systems where tests showed tap water containing more than 40 ppb, more than double the EPA’s limit, which itself is unrealistically high.

At the Orange Center School near Fresno, California local officials let children keep drinking the water for years despite tests that showed excessive levels of lead. The school skipped testing for nine years after a finding of high lead levels in 2003. In 2012 tests showed elevated lead levels, but school officials let children continue drinking the water. Two years later the state ordered the school to stop using the water and began shipping bottled water to students until the district connected to the Fresno water system.

The problem is not limited to small cities or rural areas. In April, water testing in the city of Detroit revealed that 19 public schools had elevated levels of lead or copper. One water sample at Brown Academy showed lead levels of 1,500 ppb, 100 times the EPA limit of 15 ppb.

Despite the pressing urgency, the amount of money available for water system upgrades is tiny compared to the need. The EPA estimated in 2013 that some $64.5 billion is needed over the next 20 years to maintain small water systems. In 2016 the revolving fund allocation for water systems of all sizes was less than $1 billion.

In the wake of the USA Today report federal, state and local officials went into damage control mode, feigning shock and outrage at the disastrous state of US water infrastructure. While calling for tightening lead testing standards and notification, none of the proposed legislation actually provides additional funding for water infrastructure, particularly for small, cash-strapped communities in impoverished areas.

In relation to the Flint water crisis, the US Senate approved legislation this week appropriating a token $170 million to address needed infrastructure upgrades in the city. The money is a relative drop in the bucket compared to the estimated cost of replacing lead pipes in the city, which by some calculations will reach up to $1.5 billion.

Meanwhile, a federal appeals court on Friday ruled that the State of Michigan must make regular water deliveries to homes in Flint that do not have a working lead filter. The administration of Republican Governor Rick Snyder has ignored two previous court rulings mandating the delivery of bottled water, claiming the cost would be prohibitive and that it is unnecessary since the city’s tap water now meets federal standards.

Activist Melissa Mays of the group Water You Fighting For? told a press conference Tuesday that she questions the methods state officials are using to determine if Flint water is safe to drink. She said that many residents had results coming in above the federal action level of 15 ppb—in at least one case, as high as 1,700 ppb. She wanted every home in Flint tested.

“We have too many vulnerable people slipping through the cracks right now and there are too many high numbers … I don’t care if it seems unrealistic because it’s unrealistic to us to think that everything’s OK when there’s not the data to back it up,” Mays remarked.