Washington, D.C. ranks as the fifth rattiest city in America, a position it has held for six consecutive years. The problem is getting worse fast: rodent complaints filed through the city’s 311 system in 2024 were 155% higher than 2019 levels, and over the past 12 years, those requests have increased by a factor of 12.5. The capital’s rat population isn’t just a nuisance. It’s the product of aging pipes, warmer winters, dense development, and a booming restaurant scene all working together.
An Underground Highway Built for Rats
The single biggest factor behind D.C.’s rat problem is what lies beneath the streets. The District sits on top of roughly 6.7 million linear feet of sewer pipe, and nearly three-quarters of it was installed more than 50 years ago. Some of it dates back over a century. Norway rats, the dominant species in the city, thrive in underground tunnel systems, and D.C.’s aging sewers give them exactly that: a sprawling, climate-controlled network of nesting sites and travel corridors that connects neighborhoods block by block.
The pipe material matters, too. About 77% of the city’s sanitary and combined sewer system is made of vitrified clay, a material that cracks and degrades over time. Rats can gnaw through weakened joints and exploit structural breaks to move between the sewer system and the surface. Older brick and stone pipes are even more vulnerable, though they make up a smaller share of the total. The smaller the pipe diameter, the more useful it is to rats, and more than 77% of the system consists of pipes 24 inches or less across, a size range with low water flow and high potential for rodent activity.
Certain neighborhoods sit on combined sewers, which carry both stormwater and wastewater in the same pipe. Areas like Adams Morgan, Georgetown, and Capitol Hill use this older design. Some of these larger combined sewers contain open-trough sanitary lines running inside them, and these have been documented as active rat corridors. The result is that rats don’t just live underground. They move through the city underground, popping up wherever a cracked pipe, open catch basin, or construction project gives them access to the surface.
Warmer Winters Mean More Rats Year-Round
Rats are small mammals that struggle to regulate body temperature in true cold. Historically, harsh winters acted as a natural check on urban rat populations by killing off weaker animals and shortening the breeding season. That check is weakening. A 2025 study published in Science Advances found that cities experiencing greater temperature increases over time saw correspondingly larger increases in rat populations. Warming temperatures extend the window during which rats can forage above ground and actively breed, which directly supports population growth.
D.C.’s mid-Atlantic climate has shifted noticeably over recent decades, with milder winters and longer warm seasons. The urban heat island effect compounds this: pavement, buildings, and underground infrastructure radiate heat, keeping city temperatures several degrees above surrounding areas even on cold nights. For rats, this means more months of active reproduction and more surviving pups per litter making it to adulthood. A single pair of rats can produce dozens of offspring in a year under favorable conditions, so even a few extra weeks of mild weather compounds quickly across the population.
More People, More Food, More Waste
Rat populations track human density closely. More people per square block means more garbage, more restaurant waste, more outdoor dining, and more opportunities for rats to feed. D.C. has seen steady population growth and significant new development over the past two decades, and the restaurant and food service industry has expanded alongside it. Every new dining establishment generates organic waste. Every construction project disturbs underground burrows and pushes rats to the surface, often into neighboring blocks that previously had manageable numbers.
The same Science Advances research confirmed the pattern: cities with denser human populations and more urbanization saw larger rat increases, independent of climate effects. D.C. checks both boxes. It’s a compact city with high population density, and it continues to add residential and commercial development in neighborhoods that already sit on vulnerable infrastructure.
Where the Problem Is Worst
The rat problem isn’t evenly distributed. In 2024, four neighborhoods in northeast D.C., Edgewood, Bloomingdale, Truxton Circle, and Eckington, together logged more than 1,400 rodent inspection and treatment requests. That cluster alone accounted for over 8% of all citywide complaints. These neighborhoods share a common profile: older rowhouse construction with back alleys, mature trees, aging sewer connections, and a mix of residential and commercial activity that produces steady food waste.
The pattern repeats in other historically dense parts of the city. Neighborhoods built in the late 1800s and early 1900s tend to have the oldest underground infrastructure, the most structural vulnerabilities, and the highest complaint rates. Newer developments on the city’s edges generally have modern sewer systems with fewer entry points for rodents, though construction activity in those areas can still trigger temporary spikes.
Why the City Struggles to Keep Up
D.C. has run organized rodent control programs for decades, but the scale of the infrastructure problem makes sustained progress difficult. Effective long-term control requires coordination between pest management, sewer maintenance, and construction oversight. Camera surveys and smoke tests can identify structural breaks in sewer lines where rats enter and exit, but prioritizing and repairing those breaks across thousands of miles of pipe is enormously expensive and slow.
Surface-level treatments like baiting and burrow elimination reduce visible rat activity in targeted areas, but rats simply relocate if the underground network remains intact. Catch basins, the grated drains along curbs, need regular cleaning to remove debris that rats use as nesting material, yet historically the city has cleaned them on 18-month cycles. That schedule leaves long windows for rats to establish themselves.
Construction and development projects add another layer of complexity. Digging disrupts established colonies and scatters rats into surrounding blocks, creating new hotspots faster than treatment crews can respond. Residents in neighborhoods adjacent to major construction sites often report sudden, dramatic increases in sightings, even if the area had been relatively quiet before.
How D.C. Compares Nationally
Pest control company Orkin’s annual survey has ranked D.C. in the top five rattiest cities in America every year since 2019. Only Chicago, Los Angeles, New York, and San Francisco rank higher. All five cities share the same basic recipe: old infrastructure, dense populations, mild or moderating winters, and massive food service industries. D.C.’s relatively small geographic footprint actually concentrates the problem. The city covers just 68 square miles, meaning its rat population is packed into a much tighter area than sprawling cities like Los Angeles.
The 12.5-fold increase in 311 rodent complaints over 12 years reflects both a growing rat population and growing public awareness. As residents become more familiar with the reporting system and less tolerant of the problem, complaint numbers rise even beyond what population growth alone would predict. Still, the underlying trend is clear: D.C.’s rats are multiplying faster than the city’s control efforts can contain them, driven by infrastructure decay, climate shifts, and continued urban development that shows no sign of slowing.