A lot of water seems to be spilling out of leaky pipes around Falls Church lately.

Since mid-July, three water mains have broken in the Falls Church water system, which serves 120,000 customers in the city and Fairfax County.

On July 13, an eight-inch cast-iron pipe cracked off Gallows Road in Merrifield. Ten days later, a huge 20-inch main split and spilled hundreds of gallons of water all over the intersection of Kirby Road and L'Ambiance Drive in McLean.

Falls Church Public Utilities Director Bob Etris said there had not been a break that dramatic in nearly a decade. It took 15 hours to fix (the water had to be turned off in that area during that time) and required replacing 18 feet of pipe.

Then on Aug. 2, the pipes were bursting again; this time, a six-incher fractured close to Tucker Avenue and Youngblood Street in McLean.

Why breaks occur in the middle of the summer is something of a mystery to water officials. By far, the majority of breaks occur in fall or spring, when sudden changes in temperature put pressure on cast-iron pipes, Etris said.

Etris chalked up the latest breaks to coincidence rather than a developing pattern of weakness throughout the system.

In the fall and spring, sometimes as many as four or five breaks will happen on the same day, he noted.

"If I had to put a number on it, I would say 5 percent of our breaks occur during warm weather," Etris said. "So it is not the norm. You can have a contractor [accidentally] cause the break, and sometimes it just happens."

Last year, the Falls Church water system, which has about 385 miles of pipe, counted 125 breaks in water mains of all sizes.

By comparison, the Fairfax County Water Authority, with 3,135 miles of pipe, had 322 main breaks in 2003. The Fairfax system serves about 780,000 residents in the county, according to Jeanne Bailey, the agency's public affairs officer.

After hearing how many breaks the Falls Church system had last year, she said the number did not seem extraordinary.

Falls Church, however, isn't taking chances with its pipes, since some of them date to the 1940s. Every year, the city replaces sections of its older cast-iron mains with ductile iron pipes, which are not as prone to breaks. The program costs $2 million a year.

Still, even new pipes will break. When water near freezing temperatures gets caught inside pipes, sometimes there's nothing officials can do.

And on some occasions, pipes will break for no apparent reason, such as the dramatic split of the 20-inch main in McLean late last month.

"Sometimes we don't have a good explanation," Etris said.