BGS has been carrying out investigations of the baseline chemistry of groundwaters from selected aquifers or aquifer blocks across Britain. These have served to:

• characterise the inorganic chemistry of the groundwaters
• identify controlling processes, including natural geochemical reactions and likely pollutant inputs
• quantify changes with time
• establish the likely ranges of baseline concentrations under differing hydrogeological and geochemical conditions (e.g. with varying redox conditions and residence time)

The investigations have included assessment of archive data for groundwater chemistry, rainfall chemistry and aquifer chemistry and mineralogy as well as analysis of a representative set of new groundwater samples for a comprehensive suite of major and trace elements. Field determinations are carried out for acidity/alkalinity (pH), electric potential (Eh), dissolved oxygen, electrical conductance and groundwater temperature. Chemical analyses of newly collected samples are carried out in the BGS laboratories. These are conducted by a range of analytical techniques, including inductively-coupled plasma optical emission spectroscopy (ICP-OES), inductively-coupled plasma mass spectroscopy (ICP-MS), ion chromatography, carbon analyser and mass spectrometry. In some cases, subsets of samples have been analysed by gas chromatography for chlorofluorocarbons (CFCs) and sulphur hexafluoride (SF₆).

Results are presented in a series of baseline reports. Findings of the investigations are of value to water regulators in their remit to implement national and European legislation as well as to water users and prospective users.

• Download Baseline reports for England & Wales
• Baseline Scotland: groundwater chemistry data

• National Physical Properties & Processes Laboratories
• Inorganic geochemistry laboratory
• G-BASE
• Groundwater science
• Groundwater quality