More than 1,000 protesters rallied outside Cobo Center over shutoffs by the city's water department.
The protest is led by National Nurses United, which says the shutoffs pose a public health emergency. The group and others seek an immediate end to them.
The group will march eight blocks, passing Detroit banks and City Hall before ending at Hart Plaza.
But Detroit Water and Sewerage spokesman Greg Eno says the city-owned utility has no plans to stop the shutoffs on accounts 60 days or more past due.
The water department stepped up the shutoffs in March to collect some of the nearly $90 million owed by residents, businesses and other customers with past-due accounts. Through June, more than $43 million was owed on over 80,000 city residential accounts.
Forty to 50% of Detroit Water and Sewerage bills are deliquent.
Water officials say they are working with customers who have "legitimate" problems paying their bills.