Biodiversity and catchment management

Catchment Management

At Cambridge Water, we’re committed to providing a consistent supply of high-quality water to all of our customers now and for future generations. This means taking care of the environment to ensure that the water we provide is safe to drink and of the highest quality.

Our drinking water is taken from the Chalk aquifer which lies to the south and east of Cambridge. One advantage to using groundwater for our drinking water supplies is that the layers of rock naturally filters the water, so the raw water often  requires very little treatment. However, many of these sources have been deteriorating in quality over a number of years due to rising nitrate concentrations in the aquifer, which cannot be filtered out by the Chalk.

A catchment is an area where water is collected by the natural landscape. In a catchment, rainfall not used by plants either infiltrates into the groundwater or as surface runoff; eventually flows into surface water systems such as streams rivers, lakes and the ocean

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

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

All of the Cambridge Water sources have seen an increase in nitrate concentrations and the trend is continuing to increase. The nitrate is believed to have come from the land uses in the catchment, mostly agriculture. A lot of the nitrate concentrations that we are seeing at the moment are a historical issue due to the time delay of substances working through the various layers of rock.

We are currently working with farmers in our catchments to try and reduce future nitrate concentrations and to hopefully reduce the risk of any other water quality issues such as pesticides. You can find out more about our work with farmers and our SPRING scheme here.

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

Up until recently we have relied on ‘blending’ raw water that has exceeded the legal limit for nitrate but unfortunately we are now reaching a point where our ‘low-nitrogen’ water is 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 of our sources to help ensure we meet the legal limit for nitrate concentrations.

Using treatment to remove the problem is the not the most sustainable nor cost effective way of ensuring the long term protection of our drinking water, as treatment works have additional operating costs, require maintenance and increase our carbon footprint. 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. Catchment management means that we will work collaboratively with landowners, partnerships and local interest groups by raising awareness of the problem of nitrates and working to lower the input of nitrogen at the source.

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