Covers devices used to treat water intended for use in the delivery of hemodialysis and related therapies, including water used for: (1) the preparation of concentrates from powder or other highly concentrated media at a dialysis facility; (2) the preparation of dialysis fluid, including dialysis fluid that can be used for the preparation of substitution fluid; (3) the reprocessing of dialyzers for multiple uses. Included within the scope are all devices, piping and fittings between the point at which potable water is delivered to the water treatment system, and the point of use of the dialysis water. Addressed to the manufacturer and/or supplier of water treatment systems and/or devices used for the express purpose of providing water for hemodialysis or related therapies.