Access to clean water is a basic human right. Yet for 14 million US households, or 12 percent of homes, water bills are too expensive. And as the cost of water rises, even more Americans are at risk of not being able to pay their monthly water bill.

According to a 2017 paper from researchers at Michigan State University, water prices will have to increase by 41 percent in the next five years to cover the costs of replacing aging water infrastructure and adapting to climate change. That will mean that nearly 41 million households — or a staggering third of all US households — may not be able to afford water for drinking, bathing, and cooking by 2020.

There is no law that guarantees water access for poor Americans. And most financial assistance is left to the discretion of individual water utilities. So customers who have fallen behind in payments can have their water services abruptly shut off.

More than 50,000 households in Detroit have lost water services since 2014 because they couldn’t pay their bills. Flint, Michigan, which is still in the throes of a lead poisoning crisis, is now threatening to terminate water services for more than 8,000 people who haven’t paid their bill.

But it’s not just the Michigan urban poor who are at risk.

The researchers found thousands of other census tracts around the US where the median income was low enough to put people at risk of not be able to afford their water bills as water prices continue to rise.

The Environmental Protection Agency has recommended that water and wastewater services should not make up more than 4.5 percent of a household’s income. So the researchers considered places where the median income was less than $32,000 in 2014 to be high risk (in dark blue), while places where the median incomes range from $32,000 to $45,120 (in light blue) were at risk. In all, we’re looking at a huge number of areas across the US where millions of households are struggling to pay their water bill.

A third of American households might be unable to pay their water bill by 2020

According to the American Water Works Association, on average we pay less than half a penny for a gallon of water. But “it doesn’t mean there aren’t families that struggle to pay,” said Greg Kail, the communications director at AWWA.

And people in poorer states like Mississippi, Louisiana, Alabama, Kentucky, and Arkansas are especially at risk of not being able to pay their water bills, according to Elizabeth Mack, a researcher at Michigan State and the co-author of the paper, which appeared online in the journal PLOS One. In Mississippi, nearly 75 percent of the state was either at high risk or at risk. But the problem wasn’t concentrated in just rural areas either. Mack also found 81 percent of high-risk census tracts were located in metropolitan areas.

And if water rates increase by 41 percent in the next five years (as Mack thinks they will), the number of households unable to pay their water bill will nearly triple, from 14 million to 41 million.

The 6 percent increase reflects the actual change in water costs between 2014 and 2015, and the 41 percent increase is how much water prices rose from 2010 to 2015. (Mack is assuming water rates will increase at the same clip as they did from 2010 to 2015 and that median household income will remain flat — reasonable considering household income has seen no real growth in the past 20 years.)

“I don’t know why people haven’t paid more attention to this,” she said.

The huge costs of repairing water infrastructure is forcing water rates up

After World War II, America went on something of an infrastructure kick, building an expansive network of water pipes in cities across the country. But now these pipes are more than 60 years old and in many instances are in desperate need of repair.

Federal funding for water infrastructure has fallen from more than 60 percent in the late 1970s to just 9 percent now. And civil engineers estimate the price tag for overhauling America’s drinking water system and bringing it up to code will be at least $1 trillion over the next 25 years. Add to that the estimated $14 billion to $26 billion needed to adapt water systems to climate change by 2050.

Tracy Mehan, executive director of government affairs at AWWA, has pushed for an increase in federal funding but says we can’t avoid higher water rates. “We’ve coasted for decades in most places around the country. Our rates are half that of northern European cities,” he said. “Rates are going up and need to go up.”

Just how far up? Mack thinks annual water bills will increase by nearly $600 over the next five years to around $2,000, or $169 per month. (The average annual bill is currently $1,440, or $120 a month.)

What’s more, Mack says her estimates are conservative compared with those of Circle of Blue, a nonprofit focused on issues of water affordability. Circle of Blue found cities like Austin; Charlotte, North Carolina; Chicago; San Francisco; and Tucson, Arizona, all experienced water rate hikes greater than 50 percent within the past five years.

Here’s Circle of Blue’s map of water prices in 30 major US cities as of 2015. Atlanta leads the nation with the most expensive monthly water bill — $326 on average. (Circle of Blue calculated monthly water bills for a family of four using roughly 12,000 gallons of water a month, which the EPA has estimated is average household use).

This means for a family of four making $32,000 in Atlanta, an annual water bill of $3,912 eats up more than 12 percent of their income — and again, that’s three times what the EPA recommends a family should be paying for water.

Some cities are restructuring water rates based on income, which could help struggling families

One possible solution that Mack said is gaining traction to help low-income Americans address affordability issues is restructuring water rates based on income.

Restructuring water rates involves determining the number of gallons a customer can use each month for a prenegotiated fee. If a customer uses more than the set amount, they pay a penalty or overage fee. Recent research shows that when utilities restructure rates, it can help offset the rising costs of water service.

But as cities move to restructure rates and redistribute costs, it’s important they implement lower cost rate structures for low-income households. Otherwise, restructuring rates can backfire and poorer households can end up with an even higher bill than what they were paying before. Mack says a food stamp equivalent program for water services or some kind of low income subsidy could help.

“People could think about setting up lower fees for different income brackets,” she said. “Set a minimal level of necessary water use [for lower-income households] and if you use more than that, from that point you pay more.”

And some cities like Philadelphia are already moving to implement a rate structure that offers low-income families reduced water rates. In July, the city is rolling out a tiered rate structure for customers whose incomes fall at or below 150 percent of the poverty line.

With a third of Americans at risk of not being able to pay their water bill by 2020, we need to move quickly to invest in infrastructure and restructure water rates in a way that doesn’t negatively impact low-income customers. Otherwise we could be looking at a national crisis similar to what’s playing out in Detroit and Flint — thousands of families losing their water because they can’t afford their bill.