What are the main sources of Borehole Contamination.
The main source of borehole contamination is from leaking septic and fuel tanks and from animals kept close to the borehole location. All borehole installations must be properly sealed below ground level either by grouting or concreting a steel casing into a clay type zone or into rock head or by sealing any PVC casing or well screen to at least 5 metres below ground level.
For more information there are several useful guides which are available on The Well Drillers Association website. Guidance Notes for the Construction of Boreholes for Water Supply provides good general advice on contamination protection, including the recommended methods for manhole construction.
The Environment Agency also has two related publications called “Water Supply Borehole Construction and Headworks – Guide to Good Practice” and “Groundwater Source Protection Zones”.