The source of the rupture has been identified in the pipe break that has caused nearly two million people in the Boston area to lose their supply of clean drinking water.
"The extent of the damage is not as great as we feared,'' Gov. Deval Patrick said at a press conference this morning. However, he refused to give a firm estimate when people could drink water again, but said he anticipated it would be "days not weeks."
State officials also said this morning that the state is buying 2.5 million gallons of drinkable water that will arrive on tractor trailers, each holding 55,000 gallons of water and costing $8,000. The water will largely be for vunerable populations of people such as the elderly that cannot get to stores to buy water. The state will also ask federal help in securing water supplies if they cannot find enough.
Yesterday, supplies of bottled water in stores throughout the region dwindled and in a sure signs Greater Bostonians lives had been disrupted, scores of Dunkin' Donuts had no coffee for sale.
Public health officials said any illnesses from drinking contaminated water would not show up for about a week.
The leak was in a steel coupling, or collar, linking two pipes. The area has been excavated and last night, a new collar was brought to the scene in two pieces that looks like a ring. The bottom half was being welded this morning and the second half will be welded on later today.
But even if the patch engineers and contractors are working on holds, it is unclear if there is other damage throughout the roughly 150-foot long pipe from the massive water leak that gushed 265 million gallons over about eight hours yesterday. Pressure testing the system could begin tonight.
If the patch works, there will still need to be several days of tests to make sure the water is safe to drink, said Frederick A. Laskey, executive director of the MWRA.
As workers frantically toiled to fix the pipe yesterday, questions turned to why it happened. The coupling that failed is a standard component of underground pipes, including throughout the MWRA system.
"Our goal is to get it fixed and then figure out what happened,'' said Laskey. The failure could be from a number of things, including the design, construction or installation of the piece.
A representative of Barletta Companies of Canton, who installed the collar - and is in the process of fixing the pipe said he had "no idea" what went wrong. The broken collar washed away into the Charles and a hunt is on for it so authorities can examine in for possible clues why it failed.
The pipe abruptly burst Saturday, prompting authorities to declare a state of emergency and to impose a sweeping order for homeowners and businesses to boil the untreated water now flowing from their taps.
Patrick said residents in Boston and 29 other communities east of Weston should boil water for at least a minute before drinking it to avoid the risk of getting sick.
The crisis began around 10 a.m. when the pipe sprang a leak, which worsened throughout the afternoon and eventually cut off Greater Boston from the Quabbin Reservoir, where most of its water supply is stored.
The MWRA said it could continue supplying water by activating a backup system that began drawing water last night from the Sudbury Reservoir, and can also tap into the Weston and Spot Pond reservoirs if necessary. The backup water, which one official compared with “untreated pond water,’’ can be used for bathing and flushing toilets, but not for drinking or cooking.
“This is everyone’s worst nightmare in the water industry,’’ said Frederick A. Laskey, executive director of the Massachusetts Water Resources Authority. Today, he praised residents who he said were obviously conserving water because overall use was down in the system.
Local officials across the region continued today to warn residents about the potential for contamination. At Massachusetts General Hospital, staff put up signs warning, “Don’t drink the water.’’
The governor renewed his plea this morning for neighbors to look in on vulnerable or elderly neighbors.
The “good news,’’ Laskey said, is that “we continue to maintain the flow for firefighting’’ and for toilets and other nondrinking purposes. Laskey said the backup system has enough untreated water to indefinitely supply the region.
Many questions remained unanswered.
Officials said they did not know how long it would take to restore clean drinking water to the region, but Laskey said he hopes it will be “days, not weeks.’’
Officials also said they did not know what caused the relatively new seven-year-old steel pipe to break 20 feet underground, near Recreation Road by the intersection of the Massachusetts Turnpike and Route 128.
Officials shut off the water supply into the pipe at about 6:40 p.m. Soon after, engineers discovered rubber gaskets floating above the leak, leading them to theorize that the pipe had ruptured at the coupling connecting sections of the pipe.
By 10 p.m., Laskey said engineers could see into the pipe. It was still half-full with water. But he said he was encouraged that the problem might be solved relatively soon because the coupling could be fixed more easily than the steel pipe.
“In a sense, it’s the most vulnerable point in the system,’’ said Tom Baron, an independent water systems engineer who formerly worked for the water authority.
Officials said that if they cannot repair the pipe with a temporary patch, a new custom-made pipe might have to be built. Officials had been building a backup system for Greater Boston’s drinking water system, but it is three or four years from completion. Before water was shut off to the ruptured pipe yesterday, brown water had been roaring from a massive crater in the ground, sending more than 8 million gallons an hour rushing down a hill into the nearby Charles River.
The state Department of Conservation and Recreation said the millions of gallons pouring into the river would not be a problem, even as the river’s elevation rose by 8 inches in some locations and its flow nearly doubled in a matter of hours.
“Our dams can handle this,’’ said Wendy Fox, a spokeswoman for the agency.
But Nigel Pickering, senior engineer and watershed modeler for the Charles River Watershed Association, warned that the water entering the river from the break could stir up sediment, harming fish. Laskey said it did not appear that sediments had been kicked up as of Saturday night.
Authorities said that contractors and engineers would know more about what went wrong today, when they have a chance to better inspect the pipe.
“I really don’t want to speculate,’’ Laskey said at the scene of the break. “We’ve got to get there to know.’’
Not every community was affected. Cambridge, for example, has its own water supply.
And water authority spokeswoman Ria Convery said that the authority, working with the Boston Water and Sewer Commission, was able to reconfigure the water pipe lines in the Longwood Medical Area. That temporary fix allowed four major hospitals in the area — Children’s Hospital, the Dana-Farber Cancer Institute, Beth Israel Deaconess Medical Center, and Brigham and Women’s Hospital — to go about business as usual, without having to resort to bottled water, she said.
Eric Moskowitz and John M. Guilfoil of the Globe staff, and Globe correspondent Caitlin Castello contributed to this report.
On the beat
Columnist Shirley Leung says Boston mayor-elect Martin J. Walsh should focus on middle-class housing. Read more