Pests news from BPCA

30 April 2020

Floods! Work study and opportunities for pest professionals

Technical | PPC99 May 2020

Back in January and February much of the UK was underwater. Homes, businesses and public spaces were flooded, bringing with them a wave of pest-related issues.

BPCA member, Killgerm, has produced a handy guide for pest management companies looking to help out with the effects of flooding problems.


  • Floods can create the perfect environment for rodent and insect pests
  • Leptospirosis and Coliform bacteria are associated with flooding and increase the chance for disease
  • Floodwaters debris create excellent breeding conditions for houseflies, mosquitoes, other flies and insects
  • After flooding, many rodents are displaced from their natural habitat
  • You should follow The Environment Agency safety precautions when working around floods.


Floodwaters often bring mass devastation, flooding homes and other premises, causing stress and deprivation.

The presence of floods also frequently heightens the risk of disease.

Floods can create the perfect environment for pests, such as rodents, since they are often displaced from sewers and burrows.

The standing water, waste, sewage and debris left behind provide ideal breeding grounds for insects such as mosquitoes and other flies.

Such favourable conditions can result in an abundance of disease-carrying and nuisance causing flies, posing a significant risk to health.


Coliform bacteria and other faecal organisms can be associated with floods, storm drains, sewer back-up incidents, etc.

Weil’s disease or Leptospirosis, carried by rodents, has been associated with flooding. Some studies have found a 15-fold risk of the disease associated with walking through floodwaters.

A report revealed that there were 42 cases of Weil’s disease reported in England in 2010. Epidemics may be associated with changes in human behaviour, animal or sewage contamination of water, changes in animal reservoir density, or following natural disasters such as floods.

It is important to be aware of the flu-like symptoms caused by a Leptospirosis infection. Those who may be exposed to Leptospirosis should take relevant precautions listed on the ‘Leptospirosis (Weil’s disease)’ cards, which should be kept with you at all times.

Insect pests

Filth and debris left by the floodwaters create excellent breeding conditions for houseflies, mosquitoes, other flies and insects associated with decaying organic matter.

Those insects may be capable of causing significant nuisance and in some cases spreading disease.

Control of such insects involves removal of the breeding source, which can be standing/stagnant water, and accumulations of organic matter in drainage systems.

Flooded cellars, in particular, can harbour Culex pipiens biotype molestus, a human-biting mosquito.

Accumulations of decaying organic matter can provide breeding sites for a number of different ‘drain’ flies that may be involved in disease transmission and can certainly reach nuisance proportions. Such families of flies include the lesser dung flies family Sphaeroceridae, fruit flies family Drosophilidae, owl-midges or bathroom flies family Pyschodidae, fungus gnats family Mycetophilidae, sciarid flies family Sciaridae, window gnats family Anisopodidae and others.

Sites that are very wet, for at least part of the year, may favour the development of biting midges, family Ceratopogonidae.

Flooded cellars, in particular, can harbour Culex pipiens biotype molestus, a human-biting mosquito.


Rodent pests

After flooding, many rodents are displaced from their natural habitat. The rodents will then find areas that provide food, water and harbourage. Inevitably, rodents enter houses, sheds, barns, and other buildings.

Flood-damaged premises are particularly attractive and provide easy access for rodents.

These unwelcome rodents may cause damage to property directly by gnawing or indirectly by depositing faeces and urine. Rodents can threaten public health, as they may carry diseases such as E.coli, Salmonella and leptospirosis.

The high instance of recent flooding in the UK has increased concern regarding exposure of householders to these diseases and rodent control is likely to become increasingly important.

General safety precautions

The Environment Agency recommends the following Safety Precautions when working around floods:

  • Wear protective clothes, sturdy boots and waterproof gloves and face masks when handling debris
  • Floodwater may be contaminated by sewage, chemicals, or rat’s urine (leading to Weil’s disease)
  • Keep your hands away from your face while cleaning and always wash your hands if you come into direct contact with floodwater or silt
  • Wash all cuts and grazes and cover with a waterproof plaster
  • Get a tetanus jab if you are not already inoculated.

Suggested flood clean up procedure

After referring to the Environment Agency’s advice, we suggest you follow this general flow diagram to ensure a safe and efficient flood clean-up procedure:

  • Conduct COSHH and risk assessments
  • Use a disinfectant to control coliform bacteria and other faecal organisms associated with floods, storm-drain and sewer back-up incidents
  • Use a disinfectant to sterilise soiled carpet, floors and articles as part of the flood clean-up operation
  • The use of a ULV disinfectant could be valuable when contaminated matter is airborne or when large open indoor areas require space and surface treatment with a biocide, after physical removal of contaminated organic matter and prior to the application of a surface disinfectant
  • Flooding may result in rodent and/or insect infestations
  • Consider methods of rodent and insect control
  • Also consider odourcide products.

Disinfectants are also available that have been specifically formulated to deal with rodent-borne diseases, such as Leptospirosis. It is important to only use disinfectants that state an effect against the microorganisms that you are attempting to control.

Products to assist with the problems caused by flooding:

PX Parvo
Contains Chlorhexidine and QACs (<7.5%)
For use to control coliform bacteria and other faecal organisms associated with floods, storm-drain and sewer back-up incidents etc.

PX Lepto
Contains Chlorhexidine and QACs (<7.5%)
PX-Lepto is used to control the disease organisms associated with pest rodents (rats and mice) and has been formulated to help combat such microorganisms.


Contact the Environment Agency for further advice

0345 988 1188

Source: PPC99

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