A European Directive made under the Euratom Treaty in 2013 requires the monitoring for radioactivity of water intended for human consumption.
The Directive sets parametric values for radon and tritium, and the "Indicative Dose" for radioactivity, which applies to other radionuclides. There are certain exemptions for natural mineral waters and very small supplies, but the requirements otherwise extend to tap water and bottled water, and to natural and man-made radionuclides. Remediation and public information is required where the water fails parametric values.
Implementing regulations were made and came into force on 28 November 2015 for Wales, Scotland and Northern Ireland, but it looks as though full implementation will be late in England. The Natural Mineral Water, Spring Water and Bottled Drinking Water (England) Regulations 2016 are expected to come into force "in 2016".
Comparable changes will also be made to the Water Supply (Water Quality) Regulations 2016 for England and Wales, which apply to public water supplies.