US · guidance
CMS SOM App. H, Tag V205
ANSI/AAMI RD52:2004 Requirements as Adopted by Reference 42 CFR 494.40(a)
5.2.8 Deionization (utilization as polisher or backup)
The usual application for a deionizer is as a polisher following reverse osmosis or as a
standby process if the reverse osmosis system fails. Use of deionization as the primary
means of purification in an outpatient facility is not recommended because of the inability
of deionization and ultrafiltration to remove certain low-molecular-weight toxic bacterial
products, such as microcystins.
Under no circumstances shall DI be used when the product water of the final bed has a
resistivity below 1 megohm-cm.
Interpretive Guidance § 494.40(a)
ANSI/AAMI RD52:2004
5.2.8 Deionization
The most common configuration for DI is to have two mixed beds in series, with resistivity
monitors being placed downstream of each bed. Upon exhaustion of the first bed, reliance for
water of sufficiently high resistivity shifts to the second bed, and dialysis operations may be
continued for a short time (up to 72 hours) until a replacement bed is installed.
History
Rev.
Provenance
- Source
- cms.gov
- Retrieved
- 2026-07-22
- Edition
- som-2026-07-22
- Content hash
4282f6de8809488e94d6e1f600507e4daacd9e0393490d70f3d1cf5ecae069cd
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