Water restrictions were lifted early Tuesday for 1.8 million residents in Montgomery and Prince George's counties, allowing them to sprinkle their lawns and wash their cars, if they dared take on historic summer heat.

The Washington Suburban Sanitary Commission restored an eight-foot-wide water main that nearly burst last week in Potomac, halting water use across the Maryland suburbs and testing the patience -- and obedience -- of homeowners.

The agency had expected to end the restrictions a day earlier, but kept them in place until Tuesday morning, while waiting for water quality samples to return.

"The restrictions were unfortunate, but necessary," said WSSC General Manager Jerry N. Johnson. "We needed to be proactive to prevent what could have been a very serious situation."

Traffic could be affected in the area near Tuckerman Lane and Gainsborough Road, where the pipe -- the largest in WSSC's system -- is located. But the water main is fully operational.

Shutting down outdoor water use, or even reducing it, was a tough sell amid sweltering temperatures and a holiday weekend.

WSSC spokesman John White said 366 people were given warnings during the more than five days of restrictions. Another four residents were handed $500 citations for repeat violations.

Without restrictions, officials feared they would not have enough water pressure to fight fires. Overall all water use was down roughly 14 percent, falling far short of the agency's 30 percent goal.

The damaged 96-inch main near was identified by fiber-optic technology being implemented throughout WSSC's system of 5,500 miles of freshwater pipes and nearly 5,400 miles of sewer pipeline. Had the pipe burst, it might have led to an episode similar to what happened in Bethesda in 2008, when motorists were stranded on River Road by a broken water main, authorities feared.