Orange Water and Sewer Authority officials are working to find out what happened earlier this week to cause a major water main break. The issue occurred early Monday morning and disrupted water availability across southern Orange County through Tuesday afternoon.

“With so much water being lost, it made it impossible to safely access the valves that would have allowed us to stop the loss of water and contain it,” OWASA executive director Ed Kerwin said in an interview Wednesday afternoon.

The initial break occurred around 6 a.m. Monday at the OWASA water treatment plant in Carrboro. Utility officials sent a message to customers around 8 a.m. advising them to use water for essential purposes only. That was followed by a boil water advisory put into place Monday morning that wasn’t lifted until Tuesday afternoon.

“And during that time,” Kerwin said, “the amount of drinking water we had in our storage tanks throughout the service area had dropped to, in some areas, essentially empty almost.

“So, while most customers still had water at their tap but under reduced pressure, the inventory of drinking water in our system was very, very low.”

OWASA officials are still working to gather information from Monday’s incident, including how much water was lost. Water was brought in from Hillsborough and Chatham and Durham counties to help get OWASA levels back to normal after the break was isolated.

“We were able to activate our interconnect with the Town of Hillsborough quickly because we were actively working and exchanging water and testing, so we knew it was safe,” Kerwin said. “That eight or 10-mile connection is normally not in service.”

That active work allowed OWASA to avoid flushing the pipes and testing the water before adding it to the local supply.

Kerwin said an 80-year-old, 16-inch pipe was the source of the leak, but officials are unsure of what actually caused the break. An independent consultant has now been brought in to look at the cause of the break and the response.

“We’re going to ask our independent consultant to call them like they see them,” Kerwin said, “look over our shoulder, evaluate our response. What went well? What needed to be improved?”

A similar review was undertaken in February 2017 when too much fluoride was added to the water at the treatment plant. The water was stopped from leaving the plant, causing customers to be without water and businesses and restaurants to shut down. The investigation into that incident returned that an unintentional key stroke error was to blame.

Kerwin said the utility learned from that event and has implemented new communication strategies that were used on Monday.

“We know in events like this having timely, accurate and actionable information is huge.”

Kerwin apologized on behalf of the utility to customers for two significant outages occurring in back-to-back years.

“Is that bad luck or is that a lack of due diligence on our part to maintain the system,” Kerwin asked. “I believe the risk of both events happening in any one year was very low, and the fact that they’ve happened in back-to-back years, I think, is very low.

“That said, we certainly understand that it’s our job to take good care of our assets.”

OWASA utilizes recognized best practices, Kerwin said, including a modeling system to prioritize pipe replacement.

“We have the balancing act of keeping our rates affordable,” Kerwin said. “We know how important that is. But we also want to make sure we’re investing our customers’ money wisely, at the right time, in the right places.”

Roughly 50 cents of every dollar brought in by OWASA is reinvested in the infrastructure, according to Kerwin.

Some customers voiced complaints on social media of water rates being higher in the OWASA service area than in some nearby communities, while southern Orange County has had to deal with two significant water outages in the last two years. Kerwin said it was hard to draw an apples-to-apples comparison when looking at neighboring communities due to other factors – including more readily available, natural water sources.

“I’m not aware any utility can guarantee uninterrupted supply, be it power, water, gas, the like,” Kerwin said. “It’s certainly our job to do our very best, as a community-owned utility, to make sure our services are as reliable as they practicably can be.”

The OWASA Board of Directors is scheduled to meet at 6 p.m. Thursday in the OWASA administrative office on Jones Ferry Road.