DETROIT — A FAMILY of five with no water for two weeks who were embarrassed to ask friends if they could bathe at their house. A woman excited about purchasing a home who learned she would be held responsible for the previous owner’s delinquent water bill: all $8,000 of it. A 90-year-old woman with bedsores and no water available to clean them.

These are the stories that keep Mia Cupp up at night.

Ms. Cupp is the director of development and communication for the Wayne Metropolitan Community Action Agency, a nonprofit contracted by the state of Michigan to work as a human-services agency for Detroit. In August 2013, with a $1 million allocation, Wayne Metro became the only program to assist residents with water bills. Ms. Cupp quickly learned that this was “by far the greatest need.”

In January alone, Wayne Metro received 10,000 calls for water assistance, many of them referred directly by the Detroit Department of Water and Sewerage. It supported 904 water customers over 10 months before exhausting its funding in June. Ms. Cupp said Wayne Metro still gets hundreds of calls a day from residents. But it has no way to help them, and nowhere to refer them.

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.