Covers devices used to treat potable water intended for use in the delivery of haemodialysis and related therapies, including water used for the preparation of concentrates from powder or other highly concentrated media at a dialysis facility, the preparation of dialysis fluid, including dialysis fluid that can be used for the preparation of substitution fluid, the reprocessing of dialysers intended for single use where permitted for multiple uses, and the reprocessing of dialysers not specifically marked as intended for single use.