Watertown is trying to get the bottom of a billing mystery that’s affecting hundreds of customers.

All of the city’s 677 water and sewer bills, taken to the post office on June 20 for mailing, have not been received by customers three weeks later, city officials report.

Payments were due on July 10.

The city has a receipt for payment and acknowledgement of delivery from the post office, saying the bills had been taken care of, Watertown City Recorder April Lamberson said.

Watertown’s mail typically goes to Nashville, even when recipients are in the Wilson County city. There is generally a 4-5 day period between when the water bills are mailed and when they arrive to customers, Mayor Mike Jennings said.

But as of Thursday morning – one day past the due date when a 20% late fee is supposed to be added – the bills still hadn’t arrived.

Jennings has announced an extension for payment without penalty for one week until July 17, he said Thursday morning.

Customers are usually subject to water being shut off for unpaid bills after the 20th of the following month after delivery.

The city will “take a look at all circumstances before we make any decisions about shutting off water,” Jennings said. He noted past exceptions to keep water on for customers with unpaid bills during times of extreme hot or cold weather.

Jennings and other city officials have tried to make Watertown’s residents aware of the missing bills through social media and simple word of mouth, the mayor said. And well over half of the city’s customers have paid their bills by coming to city call, calling in via phone or using automatic draft, which was not affected.

But, there were still 268 customers who still hadn’t paid their bill this month as of Thursday morning, Lamberson said.

Kim Vastola, owner of Barrett’s Barber Shop on the Watertown square, paid this month’s e-business’s water bill by phone.

“Some people like the security of having a bill,” Vastola said. “It got a lot of people up in arms. Now that everyone knows it wasn’t the city’s fault and it wasn’t (Watertown) post office’s fault, everyone is a little more understanding.”

Jennings and the city are still searching for answers from the postal service about what might have happened to the water bills.

Attempts to reach the postal service for comment on this story weren’t immediately successful.

“I feel good about the way people have handled it,” Jennings said. “But I want to find a way to make sure this doesn’t happen again.”

Reach Andy Humbles at ahumbles@tennessean.com or 615-726-5939 and on X, formerly known as Twitter @ AndyHumbles.