Chemicals conforming to BSEN treatment chemical
Many commonly used treatment chemicals and filter media are now covered by European Standards which are published in the UK by BSi as BS ENs. Where an appropriate European Standard exists for a treatment chemical the water undertakers are obliged to purchase these products by reference to that standard. It is the water companies’ responsibility to ensure that the treatment chemicals they use conform to the standard, either by reference to the conformity statements provided by the supplier or by their own checks. Where a European Standard exists member states are not permitted to have their own approvals. However, a member state can impose conditions of use on a chemical or media on the grounds of justifiable additional technical requirements, e.g. protection of public health. In the UK conditions of use are set for a number of treatment chemicals and these are published in the List of Approved Products. Water companies must comply with the conditions of use stated in the List. Where chemicals conforming to European Standards are mixed before being sold the resultant mixture is not considered to conform to a European Standard and approval from the Authorities must be obtained before the product is used in public water supplies
