Businesses behind on water bills to the City of Atlanta be forewarned: Your water may soon be shut off.

The Atlanta Department of Watershed Management is planning to send letters to roughly 1,000 delinquent commercial customers who owe the city about $5.5 million combined. Unless the customers develop a payment plan within 30 days, their water service will be disconnected, the agency announced Friday.

The department is pursuing the funds from commercial clients who owe more than $50,000, or who haven’t made a payment in more than a year, city leaders said.

“We are committed to instituting a fair process to collect money due to the Watershed department,” Mayor Kasim Reed said in a statement. “Every paying customer served by the City of Atlanta should know that everyone else is held to the same standard.”

Some of the customers haven’t made water payments in nearly a decade, according to a list of delinquent commercial clients released by the city. And several owe more than $100,000, with the Metro Atlanta Task Force for the Homeless topping the list with a $409,000 debt.

“We are aware we owe some money. We’re not absolutely clear on what we actually owe,” executive director Anita Beaty said Friday, adding that Watershed has cooperated with the nonprofit over the issue.

“But it’s a humanitarian aid issue. Everybody has a right to water,” she continued. “We are doing a lot of work the city and county is charged to do without any support from either one.”

Several other businesses owe six-figure amounts, according to the city. Among them: Urban Suburban Inc., a real estate development company that has a $301,000 bill. A call to the company was not immediately returned Friday. Candler Warehouses LLC is behind on at least four separate commercial accounts, each ranging between $63,000 and $178,000. The company could also not be reached for comment.

Watershed Commissioner Jo Ann Macrina said the collection efforts come as the agency expects a $20 million reduction in its annual revenue because customers are using less water, thanks to behavioral changes and energy efficient appliances.

While that’s good for Mother Earth, it’s bad for the department’s bottom line.

“That’s going to hit us pretty hard,” Macrina said. “We have to make up that amount.”

Watershed earns $560 million in annual revenue and has about $10 million in uncollected bills. City officials say that while the unpaid funds are a small fraction of the annual revenue, they push the burden to other ratepayers.

Macrina said the department has no plans to cut off water to residential users at this time.

“That’s not what we’re focused on right now,” she said. “…We want to be sure we handle this successfully.”

Macrina rebuffed comparisons to Detroit, where the embattled city’s water department has made national headlines for shutting off water to residents late on their bills.

“The mayor has always focused on a healthy business community, and we have worked with customers no matter what category they’re in,” Macrina said. “That’s very unlike what happened in Detroit.”

Watershed interim deputy commissioner Mohamed Balla said there’s a key difference between commercial and residential users: “At the end of the day, commercial customers use water to a profit.”

Watershed has come under scrutiny in recent years for sky-high water bills, prompting the department to conduct a system-wide water meter audit. The bulk of the faulty billing occurred in residential accounts, the department said.

Watershed said that subsequent reviews revealed 98 percent accuracy in meter reporting.

The department will investigate any complaints of faulty billing, Macrina said.