Portland Water District officials say an aging infrastructure could mean more massive water main breaks like one in mid-December. The Dec. 19 break on Somerset Street spilled 20,000 gallons of water per minute for 45 minutes, and caused street flooding, damage to property and a 24-hour boil order. The district provides water from Sebago Lake to about 190,000 people in 11 Portland-area communities through a 975-mile network of pipes, ranging in age from 1870 to 2012. Christopher Crovo, executive director of asset management and planning for the district, tells The Portland Press Herald, the biggest concern is pipes laid between the world wars, when there was a scarcity of metal and lower craftsmanship. Annually, the district replaces about 3.5 miles of pipe, at a cost of $3 million.