Telltale Signs of a Rat Infestation

See gnaw marks or small, dark brown droppings? You might have a rat problem. Don't worry, we can help. Call and talk to our experts about fast, effective rat control treatments.

Rats are most active at night, so you'll usually spot the signs of a rat infestation before you spot a rat. Below are the most common indicators that you have a potential rat problem. 

• Rat Droppings ↓ - Small, dark, pellet-shaped feces, typically found concentrated in areas where they feed or nest (like behind items in garages or garden sheds, in cupboards or under the sink). Rats leave droppings in areas they feel safe, so droppings are often 'grouped' in hidden areas. On average rats produce 40 droppings per day.
• Rub Marks ↓ - Dark, greasy smears or smudges along skirting boards, walls, and floor edges. Rats have poor eyesight and repeatedly use the same routes, leaving oil and dirt from their fur behind.
• Gnaw Marks↓ - Rats constantly gnaw to keep their teeth in check, leaving large, rough chew marks on materials like wood, plastics, pipes, walls, and even electrical wiring, which is a significant fire hazard.
• Nests or Burrows↓ - Finding loose nests made of shredded materials like paper, fabric, or insulation in hidden warm places (lofts, basements, behind appliances) or noticing rat holes/ tunnels dug outdoors near solid structures.
• Scratching or Scurrying Noises↓ - Since rats are nocturnal, you are most likely to hear scratching, rustling, or scurrying sounds coming from inside walls, ceilings, floors or in the attic at night.
• Unusual Odours or Footprints ↓ - A strong, stale, musky, or ammonia-like smell caused by rat urine, which becomes more noticeable with a larger infestation. Rats leave foot and tail marks in dusty, less-used areas of buildings.

If you have spotted any of the signs mentioned, act quickly to get rid of rats, and ensure the potential infestation doesn’t spread any further.

They are persistent invaders seeking food, water, and shelter, especially during the cooler winter months. They gain entry through surprisingly small openings and hide in quiet, undisturbed areas close to their food and water resources.

Rats are highly flexible and can squeeze through gaps as small as a 20 pence coin (about 20mm or 0.8 inches). They will also gnaw at small gaps to enlarge them, to gain entry to sheltered areas. Rats also exploit gaps in walls and damaged or broken drains to gain entry to buildings.

If you think rats may have got into your building, it's important to check dark, quiet, undisturbed areas of the property, (using the signs of rats guide) as these are the ideal locations where rats can harbour as they feel safe.

Rats can also find shelter and survive in outside areas, such as gardens, parks, woodland, playing fields, railway or river embankments if reliable food and water sources are nearby. Here are some key signs of rats infesting your garden and other outside areas:

• Appearance: Small holes in the ground, typically 2 to 4 inches (5 to 10 cm) in diameter. Active burrows often have a smooth, well-worn appearance at the entrance, and may have loose dirt fanned out.
• Location: Look for rat burrows near structures that offer shelter, such as:
• Underneath sheds, garages, and outbuildings.
• Under decking or patio areas.
• Alongside solid objects like fences, garden walls or building foundations.
• Inside dense vegetation, overgrown areas or woodpiles, and storage areas.

• Appearance: Rats repeatedly use the same routes to travel between their nest/burrow and their food sources. They have an innate fear of new or unfamiliar things (neophobic), so established pathways feel safer and more appealing to them. This continuous travel creates narrow, worn-down, and smooth passageways in grass, soil, or low vegetation.
• Location: The runways or rat runs are often found along walls, fences, and garden borders.

• Items Damaged: Rats will chew on various outdoor items to keep their teeth sharp and as a way to access food or shelter.
• Holes chewed into plastic compost bins, dustbins, rubbish bins or wheelie bins.
• Damage to wooden sheds, fence panels, or garden furniture.
• Bite marks on fruits, vegetables (especially root crops), and edible plants in the garden.
• Chewed hosepipes (rubber or synthetic) and irrigation pipes.

• Nests: While burrows are more common, rats may also build nests using outdoor debris.
• Appearance: Piles of shredded, soft material like dried grass, leaves, twigs, fabric, or paper hidden under cover.
• Location: Underneath woodpiles, deep inside overgrown shrubs, or in cluttered corners of sheds, garages, or outbuildings.

A rat infestation typically starts when a single rat or small group of rats are attracted to a property by the basic needs for survival, find an easy entry point, and then begin to breed rapidly. The process has three main stages: Attraction, Entry, and Establishment.

Rats are opportunistic scavengers and are drawn to any location that provides easy access to their core needs:

Food: This is the primary attractant. Sources include:

• Unsecured garbage bins or open compost piles.
• Spilled food from bird feeders or pet food left outdoors.
• Unsealed dry goods (like cereal, grains, bird food or pet food) stored in accessible pantries or garages.
  Fallen fruit or vegetables in the garden.

Shelter and Warmth: Rats seek safe, dry, and warm places, especially during colder months.

• Clutter, woodpiles, and overgrown vegetation in the garden.
• Untidy basements, attics, or storage sheds filled with cardboard boxes and debris.

Water: Rats need a consistent water supply (unlike mice, which can often survive on moisture alone).

• Leaking pipes, dripping faucets, standing water in gutters, or pet water bowls left outside.
  Rats will drink around 60ml of water per day

Once attracted, rats exploit vulnerabilities in the structure to gain access to the secure shelter and food sources inside.

Structural Gaps: Rats can squeeze through gaps as small as a 20 pence coin (20mm). They enter through:

• Cracks in the foundation or gaps in exterior walls.
• Unsealed spaces around utility lines, cables, and pipes where they enter the building.
• Damaged air bricks, vents, or loose roofing/soffits.

Self-Created Holes: If a gap is too small, a rat will use its strong teeth to gnaw and enlarge the opening in materials like wood, plastic, or plaster.

Plumbing Routes: They are excellent swimmers and can travel through sewer and drainage pipes, sometimes entering homes via damaged waste pipes or even unused toilet plumbing.

Once one or two rats gain entry, the situation quickly escalates into a full infestation due to rats' extreme reproductive rate:

Nesting: The rats find a quiet, dark spot (like a wall cavity, attic, or under an appliance) and build a nest using shredded materials (insulation, paper, fabric).

Rapid Breeding: A female Norway rat can produce multiple litters per year (average 8 to 12) with each litter containing numerous young (8 to 12 per litter). Crucially, their offspring can begin mating within just 8 weeks, causing the population to multiply exponentially in a short period.

Establishing Runways: The colony creates established, greasy travel paths (runways) between the nest and food sources, making the property a permanent home.

Increased Damage: As the colony grows, the signs become more obvious (louder scratching, stronger odour, more droppings, and increased gnawing damage).

Yes, you should be concerned about rats in your property or garden, and should take action immediately if you do find visual evidence of them - such as rat droppings, gnaw marks, etc.

Rats are generally considered pests due to the serious risks they pose to human health and property. Here are the main reasons why a rat presence is a concern:

Rats are known carriers of numerous diseases and contaminants, which they spread through their droppings, urine, saliva, and their bodies.

• Disease Transmission: Rats can transmit serious diseases to people and pets, including:

1. Leptospirosis (Weil's Disease): A bacterial infection primarily spread through contact with water or soil contaminated by rat urine.
2. Salmonellosis: A type of food poisoning caused by Salmonella bacteria carried by rats, which contaminates food and food preparation surfaces.
3. Hantavirus: Spread by inhaling dust contaminated with rodent urine, droppings, or nesting materials (though less common in the UK than in other regions).

• Contamination: Rats can contaminate far more food and surfaces than they consume due to frequent urination and defecation as they travel.
• Secondary Pests: Rats often carry external parasites like fleas, ticks, and mites, which can then infest your property and pets.

Rats' strong incisor teeth grow continuously, forcing them to gnaw constantly to keep them filed down.

• Fire Hazard: Rats frequently chew through electrical wiring and cables, which can strip the insulation and lead to short circuits, causing house fires. 
• Structural Damage: They can gnaw through many building materials, including:

1. Wood (joists, beams, skirting boards, decking).
2. Plastic and lead piping (leading to water leaks or flooding).
3. Insulation (destroying attic/ loft and wall insulation to create nests).
4. Soft metals and certain types of brick/mortar to enlarge entry points.

• Drainage Problems: Burrows near foundations and gnawing on plastic drainpipes can compromise water and sewage systems. Rats will also use damaged or broken drain or sewer pipes to access a property, requiring a sewer rats solution to limit their access.

Rats reproduce quickly and in large numbers. A small problem can rapidly turn into a severe infestation that is much harder and more expensive to control. Seeing a rat during the daytime is a strong indication that the population is large and established.

In the UK, The Prevention of Damage by Pests Act 1949 requires local authorities to keep their districts free from rats and mice. These duties can also be applied to private householders and landowners if the council deems that the rat or mouse infestation poses a risk, and that you are not doing enough to control it. It is important that you engage the services of a professional pest control company like Rentokil to provide a thorough solution.