In 2008, CMS adopted ANSI/AAMI RD52:2004 and the referenced portions of RD62 as part of the End Stage Renal Disease (ESRD) regulations. In 2011, AAMI obsoleted those documents and adopted a suite of five ANSI/AAMI/ISO documents as replacement recommendations. This dialysis user guide is designed to clarify the differences in what Centers for Medicare & Medicaid Services (CMS) requires under the ESRD regulations and the "new" ISO recommendations. It includes a "Table of Differences" to allow physicians, nurses, and biomedical staff to quickly and easily compare the CMS requirements with the ISO recommendations. The dialysis user guide can help all dialysis providers move to the use of higher quality water and support them in providing better quality treatments for individuals requiring dialysis.