Detroit borders the Great Lakes system, containing 21 percent of the world’s surface freshwater. The lakes are the source of the city’s water supply, but a growing number of residents can’t turn on the tap. Over the past three months, the water department has conducted an aggressive shut-off campaign to get more than 90,000 customers to pay $90.3 million in past-due bills. Between March 25 and June 14, 12,500 Detroit customers had their water shut off.

The average monthly water bill in Detroit is $75 for a family of four — nearly twice the United States average — and the department is increasing rates this month by 8.7 percent. Over the past decade, sales have decreased by 20 to 30 percent, while the water department’s fixed costs and debt have remained high. Nonpayment of bills is also common. The increasing strain on the department’s resources is then passed on to customers.

But residents aren’t the only ones with delinquent accounts. Darryl Latimer, the department’s deputy director, told me that the State of Michigan holds its biggest bill: $5 million for water at state fairgrounds. (The state disputes the bill, arguing that it’s not responsible for the costs of infrastructure leaks.)