There has been considerable debate regarding the use of biocide ionisation systems for use in water services over recent months, with the HSE recommending that no new installations are carried out of systems that utilise copper ionisation, which followed the Biocidal Products Directive and the National Biocidal Products Regulations 2001 banning the marketing and use of elemental copper as a biocide from 1 February 2013. Uncertainty also surrounded existing installations; although at the time assurances were given they could carry on using the systems.

The HSE made representation to the European Commission to allow the continued use of copper ionisation systems in the UK and as a result the Commission has formally granted the UK essential use derogation. This allows the product to be marketed under biocidal products containing copper (EC No 231-159-6; CAS No 7440-50-8) for Product Type 2 (control of Legionella in water for human use, such as bathing and showering water) and Product Type 5 (control of Legionella in drinking water). The Commission formally published their decision in the Official Journal of the European Union on 15 February 2014.