CHICAGO (CBS) — Many residents of West Chicago are still waiting on their city to send them a water bill. For many of them, it’s been as long as 15 months since they last had a water bill.

New software designed to save West Chicago money by allowing remote readings of water meters in late 2013 wasn’t able to backdate readings. That left West Chicago with the problem of having to manually calculate water bills based on meters that were already read in-person — a time-consuming job.

Mayor Ruben Pineda said two-thirds of water customers have since received bills. That has left many others who have not, and Pineda said those residents and businesses should receive their bills in the next month or so.

Resident Jessica Erickson was still waiting for her bill, and has been since her last water bill in October 2013. She said she’s a bit frustrated.

“Things happen. Nothing’s perfect. Software’s not perfect. It seems like it’s just gone on a little longer than necessary,” she said.

Erickson and her husband were worried about the size of the first bill they’ll receive, but Pineda said the entire bill will not be sent out at once; four-month bills will be sent out every two to three months until the system is caught up.