National methane baseline survey: results summary

Summary results, January 2015

Since the beginning of the national methane baseline survey in 2012, a total of 155 new groundwater methane samples have been collected and analysed from five areas:

A number of groundwater methane values also exist for other areas from previous research projects, in particular central and southern Scotland and parts of south Yorkshire, Nottinghamshire, Lincolnshire and areas around London. These datasets have been combined to provide a summary of methane concentrations in groundwater in these areas.

Area Concentration (mg/l) Number of samples
Minimum Median Maximum
Central/southern Scotland <0.0001 0.0036 1.68 31
Lancashire and Cheshire 0.0002 0.0025 0.091 15
Midlands and Yorkshire <0.00005 0.0008 1.32 63
Southern England <0.00005 0.0012 3.67 200
South Wales 0.008 0.034 0.0906 12
Cumbria and Northumberland <0.0002 0.00065 1.434 16
Cumbria (Environment Agency data) <0.1 <0.5 14.2 836
Lancashire and Cheshire (Environment Agency data) <0.01 <0.5 132 2842

Methane baseline samples have been collected from potable water supplies — either drinking water or groundwater quality monitoring boreholes. None of the samples in the aquifers used for public water supply have exceeded the explosive limit for methane. For additional information on research carried out by BGS on methane in groundwater apart from baseline surveys, please see our methane in UK groundwater research overview and the following key publications:

Methane in UK Groundwater

Click on the regions on the map below to see initial results from the survey. In addition to methane data, there is a regional overview of the geology, aquifers and shale gas source rocks present. Areas with adequate methane data have been split by aquifer, in addition to a regional summary. Using data collected as part of the BGS and Environment Agency The Natural (Baseline) Quality of Groundwaters in England and Wales project, there is also a brief overview of the relevant aquifer’s groundwater quality. Further information on chemical indicators and trace elements that are not included in the summary can be found in the individual baseline reports.

Click on the regions on the map below to see results from the survey up to January 2015.

Future sampling campaign

The last phase of sampling for 2014/2015 is nearing completion. We plan to sample sites around Lincolnshire and continue with quarterly sampling at selected sites around the UK to provide information on the variation of methane concentrations throughout the year.

Currently no boreholes that are suitable for sampling have been identified in Northern Ireland. There are very few boreholes that are used in this area for public water supply.

The website will be updated when all sampling has been completed.


Contact Dr George Darling for further information.