We are committed to providing a consistent supply of high-quality water to all of our customers now and for the future.

In a catchment, rainfall that is not used by plants either infiltrates into the aquifer to become groundwater or continues on the surface as runoff, eventually flowing into surface water systems such as streams, rivers and lakes.

A catchment is a defined area of natural landscape that collects precipitation and contributes to a body of water, such as an aquifer or river.

The quality of this water can be affected by activity which takes place on the land and rivers that make up the catchment area.

Agriculture, industry, waste management and water abstraction all have an impact on the catchment and the quality of the water within it.

An Overview: The Source, Pathway, Receptor Model

The catchment approach works on the model of source, pathway and receptor.

• The sources include risks such as pesticides, fertilisers (nitrates), oils, industrial pollutants etc. which can vary between catchments.
• The pathway is the route taken to the receptor. This can be via surface water or via leakage/leaching to the aquifer. This is influenced by multiple factors such as geology and weather.
• The receptor is then the receiving body – e.g. a river, aquifer and ultimately the reservoirs and boreholes/water treatment works.

This model displays how contaminants can reach our sources and provides a method of managing these risks. By understanding and tackling problems at the source we can reduce our reliance on ‘end of pipe’ treatment solutions.

Our Catchment

What's the quality of raw water like in the Cambridge region? 

Our drinking water is taken from chalk aquifers that lie to the South and East of Cambridge. The chalk layers naturally filter the water from certain contaminants and impurities, this results in high quality raw water that requires very little treatment.

Nitrogen is an essential nutrient for plant growth and is regularly applied to agricultural land as nitrate in fertilisers. Agricultural fertilisers can leach into groundwater and run-off into surface water, influencing water quality.

Historically, our approach has been to ‘blend’ water from different sources. This involves mixing water that has higher concentrations of nitrate with water that has lower concentrations to ensure all water meets the required standards. Where this is not possible, we treat the water at nitrate treatment plants.

However, due to many factors in the catchment, we have seen rising nitrate concentrations in the aquifers over the years which, compromises the quality of our drinking water supply. One of these factors is agriculture, so we are currently working with farmers in our catchments to try to reduce future nitrate concentrations and reduce the risk of any other water quality issues, such as pesticides.

What are our long-term goals for managing the quality of raw water?

We have previously relied on ‘blending’ raw water to adhere to nitrate limits but unfortunately our ‘low-nitrogen’ water is becoming too high to blend the higher concentration water to an acceptable level. Therefore, we have had to invest in ‘end of pipe’ treatments at some sources.

Our approach is to combine treatment in the short to medium term with a wider catchment approach aimed at improved land management for the long term.

We aim to rely less on ‘end of pipe’ treatment solutions and more on catchment management to improve the quality of our water.

Tackling problems at the source improves resilience for the future and allows us to be proactive rather than reactive.

This approach is not only more cost-effective and sustainable but also delivers greater benefits to the environment and our customers.

Catchment management can also provide improved control over challenging chemicals that pose difficulties for treatment works by addressing these substances at their source and along their pathways.

How are we going to achieve this?

• Collaborate – work in partnership with farmers, industry, communities, regulators (such as the Environment Agency, Natural England, Drinking Water Inspectorate and River Trusts) and other water companies.
• SPRING 2 - SPRING 2 is an Environmental Protection Scheme set up by South Staffs Water to help farmers explore catchment friendly land management. Under the scheme, farmers are able to apply for a grant of up to £15,000 per farm – towards the costs of voluntary on-farm infrastructural improvements and land management options designed to protect the environment and improve water quality. Find out more about SPRING.
• Research - conduct research in our catchments to better understand how they operate including land use within each and the associated risks.
• Take action - Actively participate in initiatives which encourage catchment-friendly use of agrochemicals and enhance biodiversity.
• Educate - Inform people about the impact catchment management can have on improving the quality of raw water through awareness-raising events and host visits to our treatment works and reservoirs.

It is all about risk identification and then working with external and internal stakeholders to reduce those risks. For more information, download our catchment management leaflet

If you are interested in finding out more about catchment management at Cambridge Water, please email the catchment management team

Useful links

Catchment Management

A guide to best practice in the catchment.

Cambridge Sources Map

A map of Cambridge source catchments.

Euston and Brettenham Catchment Map

A map of the Euston and Brettenham catchments.

Fowlmere Catchment Map

A map of the Fowlmere catchment.