Odour and mosquitoes

We are committed to being a good neighbour, doing everything we can to keep odour and mosquitoes to an absolute minimum.


In summer 2008, we completed an odour improvement project which involved covering parts of the treatment process, and installing equipment to extract and treat air from inside the covered areas.

An independent odour survey carried out by odour experts OdourNet UK Ltd in September 2008 showed that odour levels had significantly reduced.

We monitor odour at Mogden using two methods:

  • Measuring levels of hydrogen sulphide, which is one of the compounds of odour at sewage treatment works. We carry out regular site odour inspections throughout the day and night, using 13 odour monitors located in the middle and around the edge of the works.
  • Olfactometry, which involves taking samples of air from different locations around the works and studying them in a laboratory. These surveys are regularly undertaken at Mogden, both by Thames Water and the London Borough of Hounslow.


We follow a strict programme of inspections and treatment aimed at controlling mosquitoes at Mogden.

The processes we use are audited by local environmental health officers, and based on recommendations from leading independent experts.

We also work with the London boroughs of Hounslow and Richmond upon Thames to raise public awareness of mosquito breeding sites in the wider local area and how to eradicate them.

Also in this section

Mogden updates Community relations Contact us