By Pat Loeb

PHILADELPHIA (CBS) - If it seems like we’ve had an awful lot of water main breaks lately, water department officials say it may be because they’ve been large mains that effect a lot of people and  that may have something to do with the weather.

It’s pretty well-known that cold weather puts a lot of stress on pipes. In fact, water department spokeswoman Laura Copeland says 50-percent of water main breaks occur in the three winter months.

But it turns out the extreme heat we’ve been experiencing this summer is also taking its toll.

“The warmer water temperature inside the pipe may cause the materials to expand and then if you couple this with the higher water usage in the summer, it kind of adds additional stress to the pipe.”

Copeland says this affects only larger pipes — 16 inches and up — while the cold weather impacts smaller pipes. So though the number of breaks this summer is lower than in the winter, their effects have been widely felt.