To introduce common standards would be to ignore the variability of the natural quality of groundwater not only between, but also within, aquifers (eg. chloride can vary naturally from 20 mg/l to over 10,000 mg/l within a distance of 10km ).
To introduce common standards would be to ignore the variability of the natural quality of groundwater not only between, but also within, aquifers (eg. chloride can vary naturally from 20 mg/l to over 10,000 mg/l within a distance of 10km ).