A spokesman for Detroit's water system says it cited 79 customers for illegal water use in one three-day period and levied $21,750 in fees.
The Detroit Water and Sewerage Department has been cracking down on tens of thousands of nonpaying residential and business customers.
Department spokesman Greg Eno says its collection effort for July 1-3 illustrates one of the challenges that the agency faces.
The department spokesman says it's trying to collect about $90 million from about 90,000 delinquent accounts.
Running water illegally carries a $250 fee for the first offense, $500 for the second and $660 for the third.
The department says it requires that the customer pay the fee in full before it works out a payment plan for service restoration.