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Protecting our chalk streams - Proposal for a new water conditioning facility

bird, butterfly and a flower

This facility will enable Affinity Water to significantly reduce borehole water abstraction from the aquifers that feed chalk streams – unique and precious habitats – and support our commitment to restoring these rare habitats in the Chilterns and further afield. Please explore these pages and the documents available to download (see right hand side bar).

Affinity Water is committed to ending unsustainable borehole water abstraction in the Chilterns and beyond and helping conserve and restore its important chalk streams. These chalk streams are truly special habitats and home to an abundance of wildlife species, such as:

  • water crowfoot
  • flag iris
  • mayfly
  • brown trout
  • kingfisher
  • otters
  • the nationally endangered water vole.

Chalk streams are at risk of extinction as the impacts of climate change combine with increasing demand for water from a growing population. Today many English chalk streams are dry in long stretches and do not meet the objectives set out in environmental legislation.

The Environment Agency considers chalk streams as incredibly important: “English chalk streams are considered to be one of the most precious and beautiful things in the natural world, known for their clear waters, rich wildlife and for providing a beautiful place for people to enjoy”.

As we reduce the amount of water we abstract from these chalk streams, we must continue to meet demand for water within our supply area. This means we need to increase the supply of water from alternative sources.

An important part of our strategy to achieve this is to bring water down through an existing pipe network from Anglian Water’s Grafham Water reservoir, near Huntingdon. We already import water into our region from Anglian’s Grafham water treatment works. To compensate for our plans to reduce our abstraction from chalk aquifers in our region, we will need to increase the water we import from Grafham and supply this to customers who have previously been supplied from local groundwater sources.

These waters are different chemically, so we will condition the imported water to make it compatible with our pipes which have been accustomed to a water with different chemistry. The risk is for the change in chemistry to cause discolouration if no conditioning takes place, even though both sets of water are safe to drink and comply with the high-quality standards set by the Drinking Water Inspectorate.

The preferred location to do this has been identified as the existing Sundon Reservoir site. This is located between Streatley and Upper Sundon. This site has previously been operated as a water facility by Anglian Water and already has a great deal of the infrastructure we need.

Map showing the location of Sundon Reservoir

Affinity Water has applied for planning permission for this water conditioning facility, adjacent to the existing underground reservoir. Conditional planning permission has been granted in April 2022.

You can find out more about the proposals here and share your views with us on this.

Important works to preserve our unique local chalk streams

The Chilterns' chalk streams are so important that a special partnership project has been created to conserve them. Uniting all the organisations with an interest in the streams, the Chilterns Chalk Streams Project works with local people across the Chilterns to improve river habitats, improve access and enjoyment and promote the sustainable use of water.

Key documents and downloads