7 Tell-Tale Signs You Have Rats in Your Home

Rats are one of London's most common household pests, yet many homeowners don't realise they have an infestation until it is already well established. Rats are nocturnal and instinctively avoid open spaces, which means the first signs are often indirect evidence of their activity rather than a sighting of the animal itself.

1. Droppings Rat droppings are the most reliable indicator of an infestation. They are dark brown, shiny when fresh, and shaped like a grain of rice — roughly 10–20mm long. You'll typically find them along skirting boards, in cupboards under the sink, behind kitchen appliances and in loft spaces. A single rat can produce up to 40 droppings per night.

2. Gnaw Marks Rats have teeth that grow continuously and must constantly gnaw to keep them in check. They will chew through electrical cables, plastic pipes, wooden joists, food packaging and almost anything else in their path. Fresh gnaw marks are pale and rough; older ones are darker and smoother. Chewed electrical cables are a serious fire hazard.

3. Grease Marks (Smear Marks) Rats have poor eyesight and follow the same routes repeatedly, using their whiskers to navigate close to walls and along pipes. Over time, the oil from their fur leaves dark smear marks along these runs. Look for grey-brown smudges on walls, pipes and beams at low level.

4. Footprints and Tail Drags In dusty areas such as loft spaces, cellars or behind appliances, you may be able to see rat footprints or tail drag marks. Sprinkling flour or talcum powder in a suspected area overnight is a useful way to confirm activity — check for tracks the following morning.

5. Scratching and Scurrying Sounds Rodent activity is most audible at night. Scratching in the walls, ceiling or floor, particularly between 11pm and 3am, is a common complaint. In older London properties with timber floor joists, rats can move throughout the building structure with ease.

6. Nesting Material Rats build nests in warm, dark and undisturbed locations. They shred insulation, paper, cardboard, soft furnishings and other fibrous materials to create bedding. Common nesting sites include the back of kitchen units, behind water heaters, inside loft insulation and under floorboards.

7. A Musty or Ammonia-Like Smell A large rat infestation produces a distinct smell from their urine, droppings and the animals themselves. If an unexplained ammonia-like or musky odour develops in a room, particularly in enclosed spaces, rodents should be suspected.

What to Do Next If you identify several of these signs, seek advice from a suitably qualified pest professional. Treatment recommendations and follow-up terms depend on the appointed operator.