As professional gardener Helen Yoest of Raleigh drove toward Glenwood Avenue's intersection with Oberlin Road on Monday afternoon, her children saw it first: the muddy gushing of a broken water main.

Broken water pipes may be an inevitable part of urban life, but they're more worrisome and frustrating during the drought. Why, residents such as Yoest wonder, should we shorten our showers and abandon our shrubs while tens of thousands of gallons of water so often go to waste?

The break of an old 8-inch cast iron pipe Monday let an estimated 200,000 gallons of treated drinking water escape into storm sewers. That's enough wasted water for 125,000 low-flow toilet flushes -- and about one-half of 1 percent of Raleigh's daily use.

"I'm a retired environmental engineer, and I know that there will be breaks," Yoest said. "But if 200,000 gallons is a drop in the bucket, then so is hand-held watering for gardeners."

Maybe so. But though local government leaders consider irrigation a luxury in a time of drought, they can't stop water mains from breaking. So the frequent water losses are viewed as an unavoidable cost of doing business.

"There's really not much you can do to prevent them," said Andy Brogden, Raleigh's water distribution superintendent. "It's just the nature of the business."

Even so, Brogden said his crews work hard to repair the ruptures quickly. And he understands people's concern -- especially during the drought.

"That's water that we've paid to treat and pump into the system," he said. "And it's water in our supply pool that's now gone."

Raleigh is spending $2 million this year to replace old water pipes, and it plans to raise that to $3 million next year, he said.

There's little doubt it's needed, given the frequency of failures.

Water mains break every day on average in Raleigh and Durham, though they tend to spike in winter as ground temperature fluctuations cause pipes to contract and expand. The drought itself could prompt more breaks by drying the ground, some local water officials think.

Raleigh averaged 1.2 water main breaks a day from July 1 through Thursday.

Durham, a bit more than half as big as Raleigh, averaged a water main break each day from August to November, the most recent figures available from the city.

Cary's figures weren't immediately available Tuesday.

The Orange Water and Sewer Authority had 26 water main breaks from July to December, a higher rate than it experienced in 2006.

In the summer and fall, water officials thought the drought might be at the root of some of the breaks, said John Greene, OWASA's general manager of operations. As the dry ground shriveled, the pipes shifted. The frozen ground might be adding to that shifting, Greene said.

Early Friday morning, OWASA faced what turned out to be a freezing gusher on Chapel Hill's Martin Luther King Jr. Boulevard. The call came in about 1:20 a.m. when the temperature had dipped below 20 degrees.

By the time workers got to the break, fought the ice formed from the spill and turned off the valve to begin repair work, nearly 500,000 gallons of water were gone from the 8-inch pipe -- about 6 percent of the system's average daily use.

The loss seemed even greater.

"Since the drought's on everybody's mind, when they see water going on the ground everybody's mindful of it," Greene said.

(News researcher Denise Jones contributed to this report.)