In the News: Dr. Ghosh on Baltimore’s drinking water system

Baltimore’s drinking water system is fed by a network of reservoirs north of the city, including Loch Raven and Prettyboy, and water from these reservoirs travels across the city via a network of pipes.

Upal Ghosh, a professor at the University of Maryland, Baltimore County, said the city uses two main tactics to guard against the kind of contamination seen this week. First, local pumping stations keep the water moving through the system at high pressures, ensuring that the flow is too strong to allow contaminants to seep in, even where there are inevitable leaks in valves or piping.

The other “line of defense,” Ghosh said, is chlorine. The chemical purges bacteria from the water but also decays over time and must be maintained at a high level. In response to the discovery of E. coli and coliform this week, Baltimore has been has been flushing the system and adding extra chlorine.

It’s hard to speculate about whether there could be another E. coli contamination without knowing what caused this one. But water infrastructure experts we spoke with say that Baltimore’s aging infrastructure is vulnerable to a number of challenges.

“This is kind of a signal or a flare that we should be paying better attention to the water supply in Baltimore,” said Dillon Mahmoudi, a professor of Geography at the University of Maryland, Baltimore County.

Baltimore has been widely regarded as a national leader in supplying clean drinking water, becoming a model for other cities. But the likelihood of problems has increased as the system ages, Ghosh said. The average age of the city’s water mains is 75 years, with many over 100 years old. Many pumping stations have also “seen better days,” Ghosh said.

“A lot of this infrastructure lies underground — out of sight, out of mind — and there is clearly need for big investment in infrastructure all over the city,” he said.

Dr. Ghosh was interviewed for a total of three article on this topic, read them all: