The sewage treatment process can sometimes produce smells or odours. This was not a problem in the past as sewage treatment works were normally located away from residential areas.

Reducing odour from our sewage treatment works can be costly, as work involves covering parts of these sites to treat their air emissions. This is usually difficult, as our sewage treatment works were not originally designed to collect air emissions.

However, it is easier to design new sewage treatment developments to meet the high performance standards required by local authorities.

A good example of this is our Reading Sewage Treatment Works, which opened in 2005. It is one of the most technically advanced plants of its kind in the UK, costing around £100m to build, with the majority of the works enclosed to reduce odour.

What we're doing now

In 2009, Ofwat approved proposals for additional odour control measures at nine of our sewage treatment works. These measures will be installed between 2010 and 2015, significantly reducing the number of people affected by odour around these sites.

At Beckton Sewage Treatment Works, for example, we will be investing £67m to cover parts of the works. This includes installing odour-blocking covers over all 16 primary settlement tanks at the plant - an area the size of ten football pitches.

We will also be installing odour-control units at the site to clean the outgoing air, so that we can substantially reduce odour emissions by 2015.

Odours from our Mogden Sewage Treatment Works in west London have been significantly reduced by our programme of work completed in 2008 and further odour improvements are expected when the current works are completed. A study is currently under way to identify if further opportunities exist to reduce odour levels at the site.

• Find out more about Mogden Sewage Treatment Works

Interactive map

Our interactive map provides further information about what we are planning to do to reduce odour from our sewage treatment works between 2010 and 2015. We will add more details to the map as project plans are finalised.

• View our Big Map 

Planning for the longer term

We have also outlined our long-term plans for the period to 2035 in our Strategic Direction Statement, Taking Care of Water.

This explains what we think the future holds and how we will respond to this across the full range of our services. In relation to reducing or avoiding odour, these include plans to:

• Reduce customer complaints
• Monitor trends in customer acceptability of odour
• Continue with our proactive approach to managing odour

• Read more about our 25-year plan for 2010 to 2035