The term “sewer rat” commonly refers to the Norway rat, or Rattus norvegicus, a large and highly adaptable rodent found globally. These creatures thrive in urban and suburban environments, often inhabiting lower-level areas like basements, crawl spaces, and sewer systems. Their presence introduces significant risks to both public health and the physical integrity of buildings.
Disease Hazards Carried by Rats
Rats are reservoirs for numerous pathogens, making them a serious public health concern, especially when they infest human dwellings. One of the most common bacterial infections associated with them is Leptospirosis, which is shed through the urine of infected animals. Humans can contract this disease by coming into direct contact with contaminated water or soil, or by inhaling aerosolized particles from their urine.
Another significant risk is Hantavirus Pulmonary Syndrome, a potentially severe respiratory illness. Hantavirus is transmitted when people inhale airborne dust that has been contaminated with dried rat urine, droppings, or nesting materials. The digestive system is also threatened by Salmonellosis, a form of food poisoning caused by Salmonella bacteria often present in rat feces. Contamination occurs when rats walk across food preparation surfaces or directly into stored food.
Beyond these, rats can transmit Rat-Bite Fever, a bacterial illness caused by a bite or scratch, or by consuming contaminated food. They also carry ectoparasites like fleas and ticks, which can introduce other diseases, such as Murine Typhus, to humans.
Damage to Homes and Infrastructure
The physical damage caused by rat activity often results from their biological necessity to chew constantly. A rat’s incisor teeth grow continuously throughout its life, requiring the animal to gnaw on hard surfaces to keep them filed down. This habit leads to the destruction of various structural materials, including wood, drywall, and insulation within walls and attics.
One of the most concerning types of damage is the gnawing of electrical wiring, which removes the protective insulation. Chewed wires create a serious short-circuit risk, making them a common cause of house fires. Rats also chew through soft plastic piping, leading to costly water leaks and subsequent water damage inside walls and ceilings. Furthermore, their burrowing behavior, particularly around the perimeter of a structure, can compromise the stability of building foundations and concrete slabs.
Common Pathways Into Structures
Norway rats are not skilled climbers like some other rodent species, preferring to enter structures at or below ground level. They are known to be excellent burrowers, often digging deep tunnels, sometimes up to four feet, to get beneath foundation walls. Rats are capable of compressing their bodies to squeeze through spaces about the size of a quarter.
They frequently exploit utility penetrations, finding gaps around incoming water mains, gas lines, and electrical conduits. Uncapped drains in basements or floor level sewer line breaks are direct access points from the sewer system into the home. They can also enter through damaged vents, loose door sweeps, or cracks in the foundation or concrete slab.
Keeping Rats Out of Your Home
The most effective strategy against rat infestation is exclusion, which involves sealing all potential entry points to prevent access. Any gap or hole larger than a quarter inch should be secured with materials that rats cannot chew through. Recommended materials include heavy-gauge galvanized wire mesh, steel wool, or concrete mortar, as rats can easily gnaw through plastic, rubber, and expanding foam.
Sanitation is another primary defense, focusing on eliminating the food and water sources that attract rats. All food, including pet food, should be stored in thick plastic or metal containers with tightly sealed lids. Garbage bins must also be tightly secured, and any spills or crumbs cleaned up promptly to remove foraging opportunities.
Environmental control reduces nesting sites and hiding places near your home. This involves regularly removing clutter, debris, and stacked wood from the yard. Trimming back dense vegetation and shrubs that touch the house walls or foundation removes cover that rats use for travel and nesting. Addressing leaky faucets and eliminating standing water sources also removes one of the main attractants for these pests.