Proposed Water Specifications

Proposed Guidelines
National Committee for Clinical Laboratory Standards (NCCLS)

Type I Type II Type IIB Type III
Bacterial content, colony forming
units per mL, cfu/ml (Maximum)
10 10 102 N.A.
pH N.A. N.A. N.A. N.A.
Resistivity, megohm centimeter
(M_ - cm), 25°C
10 (in-line) 1.0 1.0 0.1
Silicante mg/liter SiO2 (Maximum) 0.05 0.1 0.1 1.0
Particulate matter 0.22 um filter N.A. N.A. N.A.
Organics Activated Carbon N.A. N.A. N.A.

College of American Pathologists (CAP)


Microbial Content (cfu/ml, max.)
Type I Type II Type III
Specification Resistivity -
Specific Resistance
(megohms @25EC)
a. in line 10 N.A. N.A.
b. Effluent (As Used) N.A. 2.0 0.1
Silicate (mg/liter SiO2) 0.05 0.10 1.00
pH N.A. N.A. 5.0 - 8.0
Microbial Content (cfu/ml, max.) 10 104 N.A.

1. Particulate Matter - Type I water should be "free" of particulate matter larger than 0.2 microns. "Free of particulate matter" is defined as less than 500 particles/liter which are greater than 0.2 ohms.
2. Other parameters, such as particle size, heavy metals and/or trace elements, and carbon dioxide content should be considered and monitored when appropriate for special or specific uses.
3. Organics and other contaminants may be reduced with the use of activated carbon.

American Society for Testing Materials (ASTM)

Type I Type II Type III Type IV
Total Matter, max. mg/liter 0.1 0.1 1.0 2.0
Electrical conductivity, max. umho/cm at 298 K (25EC) 0.06 1.0 1.0 5.0
Electrical Resistivity, min. M/cm at 298 K (25EC) 16.67 1.0 1.0 0.2
pH at 298 K (25EC) * * 6.2 - 7.5 5.0 - 8.0
Min. color retention time of potassium permanganate, minutes 60 60 60 10 10
Max. soluble silica Not detectable Not detectable 10 ug/liter No limit

Microbiological Classification**

* The measurements of pH in Type I and Type II reagent waters are meaningless and have been eliminated from the procedure, since electrodes used in this test contaminate the water.
** When the bacterial levels need to be controlled, reagent grade types should be further classified as follows:

Type A Type B Type C
Max. total bacteria count 0/ml 10/ml 100/ml


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