7 Signs of a Rat Infestation (and What to Do Next)

You'll usually hear or find evidence of rats long before you see one. The clearest signs are dark droppings around 9–14mm long, gnaw marks on wood and cables, greasy smear marks along walls, and scratching or scurrying noises at night. Spotting these early makes the problem far quicker and cheaper to deal with.

The signs to look for

• Droppings: dark, sausage-shaped, 9–14mm, grouped near walls or food.
• Gnaw marks: on skirting, cables, pipes, packaging and even brickwork.
• Smear marks: greasy grey-brown streaks along walls where rats run.
• Noises: scratching or scurrying at night in walls, floors or the loft.
• Nests: shredded paper, insulation and fabric in warm, hidden spots.
• Burrows: holes 6–10cm wide near sheds, compost or decking.
• Smell: a strong, musky, ammonia-like odour.

Why you shouldn't wait

A pair of rats can become dozens within months. Beyond the health risk — rats can spread leptospirosis (Weil's disease) — they gnaw electrical cables (a fire risk), pipes and insulation. The longer it runs, the more damage and the more visits to clear.

What to do next

Remove easy food sources: secure bins, clear pet food overnight, tidy clutter. Block obvious entry points — rats squeeze through a gap the size of a 50p coin. For more than a single sighting, a professional will confirm the extent, treat it, and proof the entry points so they don't return.