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PITTSBURGH (KDKA) – Thousands of robocalls went out to Pittsburgh Water and Sewer Authority customers on Monday morning saying that they were past due on their bills.

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It also said their water would be shut off within three days – unless they paid up.

But most of the customers were caught up on their bills.

Robocall: “This notice is to inform you that PWSA will be shutting off water service to your property on or after three — three days from this notice for past due water or waste water charges.”

It was a mistake, says PWSA executive director Bob Weimar.

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“Only 120 originally were to be notified they were in arrears in their bills and they were potentially subject to shutoff if they didn’t address it,” Weimar told KDKA money editor Jon Delano on Monday.

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Instead, a man-made computer error started to send the notice to all 70,000 water customers in the PWSA system.

“It’s unfortunate, but the process somehow has the ability for someone to not check a box or to uncheck a box that ultimately exposes all of our customers to that one message that should have gone to 120,” said Weimar.

Fortunately, some customers whose bills were paid on time reacted quickly.

After the robocalls went out to approximately 12,000 customers, calls came in from these customers to this call center, clogging the system and requiring waits of over 30 minutes to get a response.

But all those calls alerted the PWSA of its mistake so, says Weimer, so within 90 minutes of the first robocall, a second call went out.

Robocall: “Please disregard this message. We are working to insure it will not happen again. We sincerely apologize for the inconvenience and confusion this has caused.”

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“It was our fault,” said Weimar, “and the individual who was responsible we’ll address that appropriately.”