The lead-tainted water of Flint, Mich., has been in the national spotlight for months. News reports have shown bottles of brown tap water and found thousands of children who have lead poisoning in their blood.

Local and national political leaders have correctly noted that the Flint water crisis is a man-made disaster — a money-saving venture gone catastrophically wrong and then ignored for more than a year, despite the complaints of residents.

Flint’s crisis is also tainted by politics. Critics argue that if the contamination had been found in a white, upper-income community instead of a mostly black, low-income city, the response would have been much faster. A broader lesson is that water systems across the United States are vulnerable to contamination. Monitoring and treatment are often inadequate, out-of-date, or both.

Unsafe levels of lead have been found in water systems around the country according to a recent New York Times story. In Washington, D.C., a 2001 change in water chemistry caused lead to leach from pipes just as in Flint. That crisis saw lead levels spike to 20 times the level allowed by federal law in thousands of DC-area homes. Congress banned lead pipes 30 years ago, but millions of older homes and older cities still have drinking water moving through lead pipes.

The Times article also noted that about a third of Americans get their drinking water from utilities drawing water from streams that are not covered by clean-water laws. In the past, efforts to regulate contaminants in streams have been resisted by agriculture and mining interests that fear the costs of cleaning those waterways. This is particularly notable in the Midwest, where field runoff from agriculture is linked to chemicals in drinking water.

Amid renewed concerns over lead-tainted water, Pennsylvania’s Department of Environmental Protection (DEP) issued a statement this week calling the state’s drinking water safe. None of the 159 public water systems tested showed lead levels above federal limits.

But lead poisoning in children remains an issue. The most common culprit is paint from homes built before the 1987 ban on lead paint. The DEP said lead found in children’s blood is not coming from drinking water — it’s from children eating paint chips or inhaling dust from lead paint.

Still, critics have questioned the federal standards used to determine the safety of our drinking water. If 90 percent of the homes tested show lead levels of 15 parts per billion or less, then that water system is rated as safe.

But medical experts, the Centers for Disease Control and Prevention and the World Health Organization all agree, along with the critics, that no level of lead in drinking water is safe for children. None.

The challenge of ensuring the safety of drinking water is huge and sobering. Federal funding for the work has been reduced by 15 percent since 2006, federal grants have been slashed, and replacing lead pipes across the nation could cost between $20 billion and $50 billion, according to the EPA. That figure is a fraction of the $384 billion that the EPA estimates is needed by 2030 just to keep Americans’ drinking water safe.

Adding to that challenge is the presence of the 100 or more potentially risky chemicals and 12 microbes that the EPS says are found, or could be found, in public water systems. But, according to the EPA, these chemicals and microbes have not been thoroughly studied and are not regulated.

Across much of Western Pennsylvania, including in Butler and Pittsburgh, municipal drinking water is also threatened by rain-triggered sewage overflows contaminating the rivers that feed water systems. There have also been reports of prescription drugs being found in water systems because people flush unused drugs down the toilet, or because human waste increasingly carries residual amounts of prescription drugs that pass through patients’ bodies.

We’ve been told for years that the vast majority of Americans are blessed to have access to reliably clean and safe drinking water. That’s still true, mostly. But Flint’s crisis and similar stories from around the country suggest that making and keeping America’s public water supplies safe is a huge challenge that will require billions of dollars in public investment.

For too long, safe drinking water has been taken for granted. Like other components of America’s infrastructure, the drinking water system is in need of upgrades as well as modernized testing and treatment.

This story will not be ending soon. Flint has exposed the vulnerability of our drinking water systems, and raised awareness of the many weaknesses and the growing challenges they face, both financial and technical, going forward.