This story has been updated.

Thousands of residents in Waterbury remained without potable water on Monday, three days after a large transmission main ruptured and sent water cascading over frozen streets while crews scrambled to contain the damage.

The outage began on Friday evening, when a break in a smaller distribution pipe along Thomaston Avenue washed away the ground underneath a much larger, high-pressure transmission pipe, causing it to fail catastrophically.

The break distrupted water service to all of Waterbury — a city of over 100,000 people — as well as the smaller adjacent towns of Wolcott and Watertown.

While water was restored to Watertown and some neighborhoods in Waterbury over the weekend, crews surveying the 36-inch transmission pipe found the damage to be “more extensive” than originally thought, Mayor Paul Pernerewski said in an update on social media Sunday.

By Monday, Pernerewski said that roughly 60% of residents remained without water, mostly on the East Side, while the rest of the city was under a boil alert until officials could get water flowing fully through the system and have it tested.

“I do want to thank all of our residents for their continued cooperation,” Perneweski said. “I know that this is not an easy thing. The good news is even though the water’s not going to be potable, once the water starts flowing the sanitation issue will change.”

In order to get the water flowing to the East End, crews worked overnight Sunday to install an emergency bypass valve to divert water around the broken transmission line. However, workers soon discovered that one of the gaskets in the new valve was leaking, and needed to be welded before the water could turn back on.

Bradley Malay, the city’s superintendent of water, said he expected work on the emergency valve to be completed Monday evening. From there, he said the city would begin slowly pumping water to get rid of the trapped air within the system — while avoiding going too fast so that the pressure doesn’t overwhelm the pipes.

“The last thing we need is to break more mains further down the road because we were impatient,” Malay said. “I’m going to go slow.”

In order to aid that effort, Malay asked city residents to run their bathtubs Monday evening until they hear the air escape and the water begins to run smoothly.

If all goes according to plan, Malay said that the city could be ready to send water samples out for testing on Tuesday. It takes 24 hours for lab to process those samples, meaning if they are clean the earliest Waterbury residents could resume drinking water is Wednesday.

“That is my rainbow-in-the-sky outlook on things, but again those things are all kind of subject to how fast we can get the system flushed out,” Malay said.

In the meantime, Pernerewski announced that the city’s schools will remain closed on Tuesday. Health officials also warned that any restaurants without their own source of water independent of the public water system must remain closed as long as the boil advisory is in effect.

With the help of the Connecticut National Guard, the city set up two distribution stations for bottled water: Municipal Stadium on Watertown Avenue and Crosby High School.

By Monday afternoon, however, the demand for water had exhausted the city’s supplies.

Pernerewski said the city distributed 32,877 gallons of water Sunday followed by another 43,699 gallons in just the first two hours of Monday morning. By 12:30 p.m., he said the city temporarily closed both of its distribution sites with plans to reopen them around 3 p.m. when a caravan of 10 trucks was expected to arrive with fresh supplies.

As that deadline came and went, however, drivers in the long line of cars waiting outside of Municipal Stadium were told by volunteers that the trucks were stuck in traffic and there was no timeline for when they might arrive.

One of those drivers, 55-year-old Chris Robinson, had been waiting for nearly an hour when the news came. He said he was willing to wait a bit longer — stocks at nearby stores were already depleted, he said — but already he was trying to come up with other plans.

“I might have to go to Hartford or wherever,” looking for bottled water, he said. “I have four kids.”

Just after 4 p.m., the trucks arrived and workers began offloading pallets of water bottles.

Ashley Alicea, 25, was complimentary of the city’s response despite the delay in getting water. She said officials had worked quickly to open up showers for residents at the YMCA, and her mother had been able to pick up water from the distrubtion site during an earlier trip over the weekend.

“I think they’re doing a great job despite the complaints people have been posting online,” she said. “It’s the whole not-knowing-when-it’s-going-to-come-back that’s making me anxious.”

Pernerewski said on Monday that Waterbury has already invested $30 million over the last year on upgrades to the city’s water system, but the work was being done in segments due to the advanced age of the system. The smaller pipe that was the original source of the break last week, for example, was built in 1901.

The cost of all that maintenance has also served as a point of contention among officials in the Naugatuck Valley.

In 2018, officials in Waterbury attempted to raise rates on water the city supplied to its smaller neighbors, including the town of Watertown. The response from officials in Watertown was to continue paying the older, lower water rates while protesting the rate hike.

Waterbury sued, and in 2023 a superior court judge ruled in the city’s favor, ordering Watertown to pay $18.8 million in unpaid water bills. The town appealed the decision, only to lose again earlier this year, by which point its debts had ballooned to $34 million.

Watertown began paying the higher water rates shortly before voters in the town approved a bond measure allowing them to pay off their remaining debts. Officials have also explored the possibility of selling the town’s water system to pay off those bonds.

Pernerewski said Monday that the dispute and delay in getting payments from Watertown was not connected to any of the issues that led to last week’s break.

“It’s a frustrating situation,” he said. “I understand fully the frustrations and I share those, and I would just ask [residents] to be patient.”

“We’ve been working to find a solution as quickly as we could, and we have one at this point that I fully believe is going to work, and I think within the next few hours, you’re going to see it.”

Correction:

An earlier version of this story inaccurately reported that the city of Waterbury distributed 32,877 gallons of water Saturday. The water was distributed on Sunday.