An estimated 200,000 gallons of water spewed onto Baldwin streets when a major pipe broke overnight, forcing schools to close Friday, authorities said.

The break in a 20-inch main occurred about 3 a.m. at Anderson Street and Winona Road, right under a tree that then toppled onto a parked van, said Brian Bruce, vice president of operations for New York American Water, which serves Nassau's South Shore.

The snow and cold made it difficult for crews as they shoveled snow to pinpoint the break, then chopped ice off about 20 valves along the pipe network, he said. That took two hours, and it was about 10 a.m. before the main was shut off, he said.

"That's probably one of the worst breaks we've had this year," Bruce said afterward. He said the ground's freezing and thawing cracked the pipe.

Bruce said 200 customers were affected by low water pressure but no one lost all water. A truck was at the scene to give out bottled water to residents.

The broken pipe was a 20- inch cast-iron main installed in the 1950s, officials said.

Crews replaced a 6- to 8-foot-long section with a stronger type of iron pipe, Bruce said. Road patching was to be finished sometime Friday night, he said, and permanent road repairs will be done when spring brings warmer weather.

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The break also caused the water pressure to plummet for customers not tied to that main, including residents in Oceanside and Roosevelt and the Baldwin school district.

Baldwin school officials posted an alert on its website, saying state law requires it to be closed for the day in this situation.

No properties were flooded by the muddied water flowing past homes, Bruce said.

He said the tree that toppled got caught up in electric wires and a PSEG Long Island contractor came to cut down the tree.

"The tree was lying on the wires when I got there," Bruce said. "The van was almost acting as a barrier. Otherwise, I think the tree might have pulled down the wire."

The van owner, retired New York City firefighter Alan Arias, said he wasn't upset over the damage: "I'm just grateful I didn't get water into our house."

He said he joked with workers about whether his 2010 Ford Econoline would restart -- he bet it could because he's had Ford vans since the '80s and knows them to be strong. "It started right up," he said, "and I was able to drive it around the corner, even though it looked like a squashed cockroach."

Bruce said Arias can file an insurance claim.

"If the van hadn't been there, it could have been a lot worse," he said. "You could have had electric wires in the water. It could have gotten ugly."