24hr Contact Number 239500

Catchment Protection

Home / Your Environment / Catchment Protection

The Water Catchment Area covers the majority of the Island, and as its name suggests, ‘catches’ the precipitation which falls, and directs it through streams into the various storage reservoirs dotted around the Island. This water is then treated and distributed to customers.

The Catchment Area is therefore a vital part of the water collection and treatment process, as it essentially forms the first stage. Guernsey Water recognises this, and employs a number of staff to ensure that the Catchment Area remains free from pollution and contamination by taking a proactive approach and liaising with potential polluters.

Guernsey Water also pre-empts possible problems by releasing educational material to the public. Examples of these documents can be viewed by clicking on the appropriate titles below:

If you are in any doubt about a Catchment Area issue, or you think that you have witnessed pollution or a pollution incident, then please contact us immediately on 239500, day or night.


Guernsey Water is well aware of the threat that can be caused by pesticides entering the water supply. In order to combat this threat, our water quality team sample regularly to ensure that the level of pesticides in the water supply remain well below the prescribed safety levels.

The permissable total pesticide level in the water supply is 0.50µg/l. This is the equivalent to half a bag of sugar in St Saviour’s reservoir when full.

Through management of the water catchment area, Guernsey Water has effectively managed to keep pollution from pesticides to a minimum. We work with all sectors to ensure water pollution does not arise, including Stan Brouard (who are the main local importer of pesticides), Guernsey's Health and Safety Executive, and Jersey and UK authorities.

We also carry out annual investigations of all Island sites that use pesticides, to ensure that the chemicals are being used safely and that there is no threat of run-off into the water supply.


From Twitter

There is more water in the atmosphere than in all of the world’s rivers combined #wednesdaywaterfact https://t.co/qB5AyZ5nET
April was unseasonably cold, however, this did not stop people visiting the Millennium Walk https://t.co/Qp79zBLoPj https://t.co/TjuTZLHYAx
We have 17 raw water storage reservoirs on the island #wednesdaywaterfact https://t.co/Uw6EbsPO7l
States of Guernsey Trading Asset