CMS SOM App. H, Tag V209

5.3.2 Water storage: tank shape/configuration

When used, storage tanks should have a conical or bowl- shaped base and should drain

from the lowest point of the base. Storage tanks should have a tight-fitting lid and be

vented through a hydrophobic 0.2 µm air filter. The filter should be changed on a regular

schedule according to the manufacturer’s instructions. A means shall be provided to

effectively disinfect any storage tank installed in a water distribution system.

7.1 General strategies for bacterial control [in storage tanks]:

An ultrafilter, distal to the storage tank, or some other form of bacterial control device is

recommended.

Storage tanks are therefore not recommended for use in dialysis systems unless they are

frequently drained and adequately disinfected.

Interpretive Guidance § 494.40(a)

ANSI/AAMI RD52:2004

5.3.2 Water storage

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Internal spray mechanisms can facilitate effective disinfection and rinsing of a storage tank.

7 Strategies for bacterial control

7.1 General

A storage tank in the distribution system greatly increases the volume of fluid and surface area

available and can serve as a niche for water bacteria. It may be necessary for the user to scrub

the sides of the tank to remove bacterial biofilm if the tank design and maintenance are not

adequate to prevent bacterial proliferation.

Additional Guidance:

If existing facilities with older storage tanks can demonstrate a history of water and dialysate

cultures being below action levels, replacement of the existing tanks is not required. AAMI

recommendation at 7.1 notes that the frequency of disinfection will vary with the design of the

system, but disinfection should be performed monthly. In order to demonstrate a history of

effective disinfection procedures, the facility is expected to demonstrate acceptable results for

the most recent 3 months of water and dialysate cultures.

Bacterial control device(s) in use following the storage tank may include an ultrafilter or

individual filters in the water supply line in each patient’s dialysis machine.

If manufacturer instructions contain disinfection procedures for the storage tank, this should be

followed. Tanks which fill from the top and drain from the bottom may, in fact, drain several

times a day. The goal is to not have stagnant water. A properly designed and functional storage

tank replaces its total volume throughout the day as part of the normal operation and does not

require manual or frequent draining of the tank.