Shortly before midnight Sunday, flashing lights and the sound of heavy equipment awakened some Drybrook Road residents. Had there been an accident? Was someone hurt?

They had their answer when they went to use the water. There wasn’t any. A six-inch water main had broken, flooding the street.

Daniel O’Rourke, director of the Water Division, had no explanation for the break. He noted the road is not subject to a lot of heavy traffic and surmised because the break occurred in a low area not too far from a brook that, over time, dirt around the pipe washed out and the line collapsed.

As soon as the break was reported by fire alarm, O’Rourke said, a crew was dispatched. The break was isolated and the water shut off. Pumps were put to work and equipment and men went to work digging. A section of pipe was replaced, and by early morning water was restored to about 30 homeowners. For a while, water ran brown and there were calls. But the water soon cleared up.

The break was fixed and all that was left was to patch the road and clean up the mess, which happened Tuesday.

O’Rourke only guessed at how many breaks the division repairs monthly, maybe one or two. Sometimes weeks go by with nothing. One of the weak points in the system, one highly visible, is along the westerly end of Airport Road. There have been numerous breaks in that high-volume line.

With talks that airport expansion would result in relocating sections of Airport Road, it made little sense to replace the line. But now with the issue of a runway extension resolved, the line is on O’Rourke’s list of capital improvements.

The Drybrook break could have been one of those that was caught before water erupted to the road surface. The system has leaks.

About 12 percent of the roughly three billion gallons of water the city purchases annually from the Providence Water Supply Board is not resold to customers. Some of it is lost when hydrants are opened up to “blow off” the system to clear lines of sediment and restore flow. The Fire Department taps into the system when needed, as do department of public works crews for street sweepers.

“It is one of the best things you can do to preserve the quality of water,” O’Rourke said of blowing off lines.

Then there are leaks.

By regulation, the division is required to identify and repair the leaks when it can’t account for a loss of 15 percent of water. In the past the city has hired consultants to track down the leaks.

But, explained O’Rourke, with the purchase of equipment, the division has taken the proactive role of “listening for leaks” and fixing them before they become breaks.

“We have people who are skilled; why not be more proactive,” O’Rourke said.

The equipment consists of modules that are placed on pipes and transmit data to a reader. It cost approximately $40,000.

“It was well worth it. It has paid for itself,” O’Rourke said. He said much of the “listening” for leaks is done during the winter months to establish a list of priority repairs once the weather turns warmer.

As for another issue facing the division, that of non-payment, O’Rourke said about 600 customers are now on payment plans representing about $800,000 in delinquencies. Overall, about $4 million in unpaid bills is owed the division. He said customers are being notified they will face shut-offs if they don’t make payment or commence a payment plan.

The shut-off option was adopted in the wake of a tax sale where 2,500 homeowners faced the loss of their property for non-payment of water and sewer bills. Ward 5 Councilman Ed Ladouceur formed a committee to study the issue and recommend measures to avoid a tax sale. The city has aggressively gone after the more than 900 customers who have outstanding balances of $1,000 or more.

O’Rourke said the division had identified 75 to 100 customers for shut-offs. He couldn’t say when those would occur.