Many cities across Pennsylvania are struggling with outdated infrastructure, especially their water and sewer lines. In Pittsburgh this week, a water main break caused a safety advisory affecting 7,000 households. It’s the city’s third such warning this year.

The broken 20-inch water main left some customers without water or with very low pressure, which means groundwater could infiltrate the pipes. In a precautionary measure, Pittsburgh Water and Sewer Authority told affected customers to run their taps and then boil water before using it to drink or cook.

The system’s weaknesses are exacerbated in winter, said Bob Weimar, the authority’s interim executive director.

“The issue really boils down to this: the pipe is old…and the problem is that it will break when it is exposed to a major change in temperature.”

These vulnerabilities are representative of nearly 70 percent of the water pipes in PWSA’s system, many of which are over 100 years old.

Pittsburgh is far from alone on the issue, with many other Pennsylvania communities relying on pipes built in the 1800s. The state, though, does not track how many miles of pipeline are in what condition.

It’s unacceptable for customers to have undergone three precautionary flush and boil advisories in such a short timeframe, said Weimar.

“But we’ve taken in each case an abundance of caution to minimize the potential for any water quality problems that would affect the public,” he said. “We think that a flush and boil order is sort of a minimal impact to make sure that we preserve the health and welfare of our customers.”

Weimar added PWSA hopes to double or triple its investment in the coming year to not only replace pipes, but provide for more routine maintenance.

The flush and boil advisory was lifted Tuesday night, but officials said water main breaks of “varying severity” will continue throughout the winter.