"Nobody thinks about it because nobody sees the things," Kocher said.
Until there's a problem, that is. The city has experienced more than 5,000 water main breaks in the past four years. In February, the rupture of a 30-inch pipe under the 100 block of E. Monument St. disrupted performances at Center Stage, flooded the basement of a state building and a church, and forced the closure of sections of Calvert Street.
It's a challenge that Baltimore shares with cities across the nation, according to federal officials. Ground that shifts as it warms put stress on brittle, aging pipes. Cracks develop. Governments spend millions of dollars fixing them.
"I can't tell you where they are not facing that problem," said Steven Allbee, an expert in water and wastewater systems at the federal Environmental Protection Agency. "This is a big deal. This is a generational challenge."
In older parts of Baltimore - including downtown - the cast-iron water pipes can be as old as 100 years. Newer parts of the city have pipes that are 40 to 50 years old. Varying methods of installation and levels of pressure make it difficult to pin down their life expectancy.
Even those that don't break can leak hundreds of thousands of gallons of water each day, city Public Works Director David Scott said. He estimates that the city loses enough water each day to fill Baltimore's World Trade Center.
"If we had unlimited resources, you could replace them all," said Bob Halbert, a director at the engineering firm Rummel, Klepper & Kahl who has worked on the city's water systems for decades. "You do what you can with the scarce dollars."
Because it is both less expensive and less disruptive to fix the pipes before they break, the city has been in the process of identifying likely weak points in the system. The pipe that ruptured Tuesday was on a list of those to be repaired.
The Department of Public Works estimates the cost of needed work on the city's water, sewer and storm water systems at $2.2 billion. The figure includes $1 billion that the city agreed to spend after the Environmental Protection Agency sued, alleging that the city's 3,100 miles of sewer pipes released untreated water into the Chesapeake Bay.
