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You are here: Home / Water Quality Standards

Water Quality Standards

There are multiple professional organizations that establish specific standards according to their fields of study. The most common of these organizations are:

  • Clinical & Laboratory Standards Institute (CLSI); formerly known as the National Committee for Clinical Laboratory Standards (NCCLS)
  • College of American Pathologists (CAP) (follows CLSI standards)
  • American Society for Testing & Materials (ASTM)
  • United States Pharmacopeia (USP)

American Society for Testing and Materials (ASTM)


Standard Specification for Reagent Grade Water
 Type IType IIType IIIType Iv
Electrical Conductivity Max (pX/cm @ 25C)0.0561.00.255.0
Electrical Resistivity Min (MOhms-cm @ 25C)181.04.00.2
pH @ 25&#176C---5.0-8.0
TOC max (µg/L)10050200No Limit
Sodium max (µg/L)151050
Silica max. (µg/L)33500No Limit
Chloride max (µg/L)151050
When bacterial levels need to be controlled, reagent grade types should be further discussed as follows:
 Type AType BType C
Total Bacterial Count Max CFU/100ml1101000
Endotoxin max. IU.ml0.030.025-

Clinical and Laboratory Standards Institute (CLSI) (CAP)
  CLRWType IType IIType III
BacteriaBacteria (CFU/ml)<10<1<100<1000
Pyrogens(Eu/ML)-<0.03n/an/a
IonsResistivity (MΩ-cm @ 25C)>10>18>1>0.05 K50Ω
ColloidsSilica (ppb)-<10<100<1000
ParticlesParticles >0.2 µm (units/mL)Include 0.22 µ filtration<1 (0.22 µ filtration required)n/an/a
OrganicsTotal Organic Carbon ppb<500<10<50<200

United States Pharmacopoeia Standards (USP)

 Purified WaterWFI Water
Electrical Conductivity Max (µS/cm @ 25C)<1.3<1.3
Total Organic Carbon (TOC) (ppm)<0.5*<0.5*
Endotoxin (EU/ml)n/a<0.25
Bacteria (guideline only)<100 cfu/ml<10 cfu/100ml
* Or pass oxidisable substance test
When bacterial levels need to be controlled, reagent grade types should be further discussed as follows:
 Type AType BType C
Total Bacterial Count Max CFU/100ml1101000
Endotoxin max IU.ml0.030.25-

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Water Quality Specialists

Definitioner

Sodium
an ion found in natural water supplies, and introduced to water in the ion exchange water softening process.
PPM
the abbreviation for part per million.
PH
the reciprocal of the logarithm of the hydrogen ion concentration. The ph scale is from zero to 14,and 7.0 is the neutral point, indicating the presence of equal concentrations of free hydrogen and hydroxide ions, ph values below 7.0 indicate increasing acidity, and ph values above 7.0 indicate increasing base concentrations.
Conductivity
the quality or power to carry electrical current; in water, the conductivity is related to the concentration of ions capable of carrying electrical current.
Bacteria
Unicellular micro-organisms which typically reproduce by cell division. Although usually classed as plants, bacteria contain no chlorophyll.