CMS SOM App. H, Tag V191

6.2.4 Softeners: (Testing hardness/log)

Users should ensure that test accuracy and sensitivity are sufficient to satisfy the total

hardness monitoring requirements of the reverse osmosis machine manufacturer. Total

hardness of the water exiting the water softener should be measured at the end of each

treatment day.

Water hardness test results should be recorded in a water softener log.

Interpretive Guidance § 494.40(a)

ANSI/AAMI RD52:2004

6.2.4 Softeners

Page 51 of 420

Softener monitoring, which should be performed daily, involves testing effluent water for total

hardness to ensure that the limits established by the reverse osmosis machine manufacturer are

not exceeded. In the case of automatically regenerating softeners, monitoring also includes

verification that the brine tank contains a sufficient supply of undissolved sodium chloride and

that the control valve timer, when present, indicates the correct time of day.

Testing for hardness should be performed using an ethylenediaminetetracetic acid (EDTA)

titration test, with “dip and read” test strips, or a similar method.

The hardness test conducted at the end of the day will indicate the overall effectiveness of the

water softener under worst-case conditions and ensure that the softener is sized correctly—that

is, it has sufficient capacity, expressed in grains of calcium carbonate.

Suggested monitoring guidelines from ANSI/AAMI RD52, Table 4 include:

For softeners: monitor product water softness daily at the end of the treatment day for hardness

as calcium carbonate, <l grain/gal, unless otherwise specified by the manufacturer of the

reverse osmosis equipment.

Additional Guidance:

The water softener log may be incorporated as a part of another log kept for the water treatment

system. For hardness tests requiring color differentiation, the person performing the analysis

should be capable of correctly interpreting the results, including the ability to distinguish and

accurately identify any colorimetric or other readings. If the person cannot differentiate these

colors, an automated meter should be used.