Recent data published on 9 May showing a 10% year-on-year increase in rodent sightings across the UK. Northern Ireland recorded the biggest jump at 26%, followed by Yorkshire at 20% and the North West at 19%.
The figures have been reported as a national problem, but in London the picture looks worse than the national average suggests. Victorian drainage, dense housing, and a record-wet start to 2026 have pushed rats out of the ground and into people’s homes across the capital at a rate the headline number doesn’t capture.
The national numbers and where London fits
Rentokil’s regional breakdown puts the West Midlands at a 16% increase and Scotland at 14%. London doesn’t appear as a separate region in their published data, and it should, because the capital already accounts for a disproportionate share of the UK’s rodent reports.
Council data from 20 London boroughs recorded 76,507 rodent infestations between 2023 and mid-2025. Tower Hamlets alone logged an average of 16 complaints per day during peak periods. A 10% increase on those baseline numbers looks very different from a 10% increase in rural North Yorkshire.
Rentokil attributes the surge to two linked weather events: the record warm summer of 2025 extending the breeding season into autumn, and sustained rainfall through winter and spring 2026 flooding underground burrow systems.
Rentokil’s published commentary on the data notes that rats can swim and handle strong currents but cannot tolerate prolonged submersion. When burrows flood, the rats move.
In most of the country, displaced rats end up in fields, outbuildings, and garden sheds. London offers them basements, cavity walls, and gaps around pipework in terraced housing built over a century ago. The city has always had a persistent pest problem tied to its housing stock.
2026’s rainfall and London’s overwhelmed sewers
Joseph Bazalgette designed London’s sewer system in the 1860s for a city of roughly 3 million people. Greater London’s population is now around 9.7 million, and the basic infrastructure still relies on combined sewers that carry rainwater and waste in the same pipes.
Heavy, sustained rainfall like the UK has seen since January 2026 overwhelms those combined sewers. Storm overflows discharge into the Thames, and the underground network becomes less hospitable for the rat colonies living within it. Rats move upward through broken pipe joints, defective drain connections, and disused inspection chambers.
In boroughs like Camden, Hackney, and Westminster, terraced housing and basement flats create interconnected voids that let rodents travel between properties without ever surfacing. A problem that starts in one house can spread to neighbours through shared wall cavities and defective party-wall construction.
London Pest Control Co. has seen a clear uptick in callouts from homeowners across South and East London since February. Most cases involve rats entering through ground-floor utility rooms, underfloor voids, or damaged soil pipes. Heavy rain comes first, then scratching sounds in walls a week or two later.
Signs that rats have moved in
Rats are cautious and largely nocturnal, so you can have an active problem for weeks before spotting one. The first signs are usually indirect.
Droppings are the clearest indicator. Rat droppings are dark brown, roughly 10 to 15mm long, and tapered at each end. Fresh ones look soft and shiny while older droppings turn grey and crumble when touched.
Finding them under a kitchen unit, behind a washing machine, or in a loft space means rats have established a regular route into the property and are using it nightly.
Gnaw marks on plastic pipes, wood, or even low-grade concrete are another sign to watch for. Rats gnaw constantly to keep their incisors from overgrowing, and damage to electrical cabling is a fire risk that insurers take seriously.
Smear marks along skirting boards are harder to spot but reliable. Rats follow the same routes repeatedly, and the grease in their fur leaves dark streaks along surfaces they brush against. Run a torch along your skirting in the evening and look for brownish marks you haven’t noticed before.
Scratching or scurrying in walls, ceilings, or underfloor spaces after dark confirms that something is living in the structure. Rats are heavier than mice, so the sounds tend to be slower and more deliberate.
Why DIY treatment often fails with drainage rats
The first instinct for most homeowners is to buy traps or poison from a hardware shop. For a single mouse that wandered in through an open door, that might be enough. For rats entering through the drainage system and nesting in the building fabric, shop-bought products rarely solve it.
Rat bait sold to the public uses first-generation anticoagulants at lower concentrations than the second-generation rodenticides (SGARs) available to BPCA-accredited pest control technicians. Weaker formulations can cause bait shyness, where the rat feels unwell, connects it with the bait, and learns to avoid it entirely.
You end up with a rat that dodges your traps and is still nesting in your cavity wall.
Professional rat control starts with identifying how the rats are getting in. In London, that almost always involves a CCTV drain survey of the underground pipework.
If a broken pipe joint or collapsed drain section is the entry point, baiting alone will never fix the problem permanently. New rats will keep arriving through the same route until it is sealed.
London Pest Control Co. combines BPCA-accredited treatment with proofing work. Bait stations and entry points get dealt with in the same programme rather than one being treated and the other ignored.
The right approach is direct: find where the rats are coming in, close it off, deal with the ones already inside, and monitor for four to six weeks to confirm the problem is resolved. Anything less and you’re paying for a temporary fix.
Landlord checks for older London properties
London landlords with older housing stock should treat the Rentokil data as a prompt to inspect their buildings. Pre-war terraces and converted Victorian properties are the most vulnerable, and a building that has never had a rat problem can develop one quickly when drainage conditions change.
The Homes (Fitness for Human Habitation) Act 2018 makes landlords responsible for ensuring rental properties are free from serious pest infestations. A landlord who ignores a tenant’s report of scratching sounds or droppings is exposed to enforcement action and potential prosecution.
The practical steps are straightforward: check external drain covers and inspection chamber lids for damage, inspect the building perimeter for gaps larger than 15mm around pipes and cables, secure bin stores, and clear accumulated waste from rear yards and lightwells where rats like to harbour.
If a tenant reports signs of activity, getting a professional inspection within days rather than weeks makes a real difference. Rat populations in London terraces grow fast when food and shelter are available.
What starts as two or three animals in a subfloor void can become a serious infestation within a month.
London Pest Control Co. offers free surveys on residential and commercial properties across London and Greater London. With the way 2026’s weather is going, getting drainage and entry points checked now saves the hassle and cost of dealing with an established colony later.
