US · guidance
CMS SOM App. H, Tag V203
ANSI/AAMI RD52:2004 Requirements as Adopted by Reference 42 CFR 494.40(a)
5.2.8 Deionization (alarms/divert to drain)
An audible and visual alarm shall be activated when the product water resistivity falls
below this level and the product water stream shall be prevented from reaching any point
of use, for example by being diverted to drain. The alarm must be audible in the patient
care area. [ANSI/AAMI RD52:2004 guidance directs users to RD62:2001, Section 4.3.6]
ANSI/AAMI RD52:2004
5.2.8 Deionization
Specifically, the resistivity monitor following the final deionizer bed shall be connected to
an audible and visible alarm in the dialysis treatment area, and the DI system shall divert
product water to drain or otherwise prevent product water from entering the distribution
system should an alarm condition occur. 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)
Page 67 of 420
ANSI/AAMI RD52:2004
5.2.8 Deionization
DI has a finite capacity that, when exceeded, will cause dangerously high levels of contaminants
in the product water. Fortunately, the quality of product water from DI is easily monitored by
resistivity monitors that, when used as specified (e.g., minimum resistivity 1 megohm-cm or
greater), can prevent inadvertent operation of an exhausted deionization system.
Additional Guidance:
Except for home patients, there must be capability for either an automatic divert-to-drain system
or other means to prevent product water from entering the distribution system for any DI system
in use. DI has a very limited capacity that, when exceeded, will cause dangerously high levels of
contaminants in the product water. Due to the increased risk to patient health and safety with the
use of water from an exhausted DI tank, manually stopping the flow before the RO product water
reaches the patient may not be as sufficient as the use of an automated protection system, such as
a divert-to-drain valve.
History
Rev.
Provenance
- Source
- cms.gov
- Retrieved
- 2026-07-22
- Edition
- som-2026-07-22
- Content hash
f06a195599e2d386c05deac1895c9dd12ffac34ea8bc39dfd517f9a67ec9d753
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