By the numbers: The toll winter takes on Baltimore's infrastructure

Winter is coming. So are broken water mains, sewer overflows, newly-formed potholes and a host of weather-related infrastructure woes.

Baltimore, get ready for a few of your least favorite things this season:


Frozen pipes at home, broken water mains on the streets

Extremely cold weather can cause the water inside smaller pipes, like household pipes, to freeze. Because water expands when it becomes ice, pressure builds up within the pipes, sometimes making them burst.

Letting a thin stream of water run through the pipes loosens the pressure and helps prevent freezing, according to the city’s Department of Public Works, which lists additional winter tips on its website.


For larger water mains — underground pipes that carry water to buildings — the freezing and thawing of the soil as daily temperatures fluctuate can cause breakage. In part due to geology, this effect is more likely to happen on Baltimore’s south and east sides, according to the Department of Public Works.

In January, there were 508 water main breaks across the city and Baltimore County (including three dozen over the course of a single day), the most in single month since at least 2015.

Water main breaks in Baltimore city and county, Nov. 2017 through Nov. 2018

Water main breaks typically happen amid frigid winter temperatures. This January saw 508 water main breaks across the city and county, the highest number in single month since at least 2015.

Sewer water discharge

Approximately 189 million gallons of sewage-tainted water have flowed into the city’s waterways so far this year. Though they are most often associated with rain, sewer water overflows can also occur following heavy snowfall. In cold weather, blockages inside the sanitary sewer system can solidify and congeal inside of pipes, said Alice Volpitta, water quality manager for Blue Water, an environmental advocacy organization.

Here is a map of outflows where more than 100 gallons were discharged in the waterways, according to estimates from the Department of Public Works.

The city is under a $1.6 billion federal consent decree to reduce sewage pollution and modernize its sewer system, which was designed more than a century ago, by 2030 — 15 years after an earlier missed deadline. Last year, levels of fecal bacteria fell dramatically in Baltimore streams, though it's too early to tell if that indicates a trend.

Who is paying for this? City residents, whose water rates have doubled over the last nine years. A proposal from the Department of Public Works would add $8 a month to a typical bill for a family of three, starting in 2019.


The plan, which includes an assistance program for households with incomes below 175 percent of the federal poverty level, is to go before the city’s spending board on Jan. 9. Meanwhile, City Council President Bernard C. “Jack” Young announced a separate low-income assistance plan on Dec. 3, a bill that would cap the amount of water bills on a sliding scale for low-income households.

Pothole season

As winter winds down, “pothole season” starts up.

Potholes — much like broken pipes — form as a result of water expansion. During winter months, water seeps below the road surface, then freezes and expands. As the pavement thaws, it starts to collapse into the hole created by the expanding ice. When vehicles run over the crumbling surface, the cracks get worse and become potholes.

Typically, this happens in early spring, when day-to-day temperatures swing from cold to warm to cold — sometimes referred to as the “freeze and thaw cycle” (Mother Nature’s very own “song of ice and fire,” if you will).

The Morning Sun


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According to the city’s 311 records, which date back to 2014, 30 percent of all pothole service requests or repairs have happened in February or March.

Winter is coming, and, to paraphrase Sun reporter Kevin Rector, the road to spring is paved with potholes.


Numbers to call for weather-related issues:

Preventing & Thawing Frozen Pipes from the American Red Cross

Cold Weather Tips from the Baltimore City Department of Public Works

Baltimore Sun reporter Scott Dance contributed to this report.

To download the data and review the computer code that generated the analysis, go to