Catchment management

Cambridge Water is 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 mostly abstracted 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 filter the water, so the raw water abstracted often requires very little treatment. However, many of these sources have been deteriorating in quality over a number of years because of rising nitrate concentrations in the raw water. This is mainly as a result of historical farming practices and land use. Many of our sources are now close to, or at risk of, exceeding the limit required for nitrate in drinking water.

In previous instances where the raw (untreated) water has exceeded the drinking water limit for nitrates, our approach has been to ‘blend’ water from different sources, mixing water which has a higher concentration of nitrate with water which has a much lower concentration. However, in the future we will be unlikely to ‘blend’ our water as all of the sources are subject to rising nitrate concentrations and many of these are likely to exceed the prescribed limit within the next 30 years. Therefore, we have had to construct nitrate treatment works at some of our sourceworks which can remove large quantities of nitrogen, ensuring we maintain the consistent delivery of high quality, safe drinking water.

Using treatment to remove the problem is the not the most sustainable or 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