Maximum Contaminant Levels in Highly Purified Water

Contaminant ParameterISO 3696 (1987)

Grade 1

Grade 2

Grade 3

Ions Resistivity at 25 °C [MΩ·cm] 10 1 0.2Conductivity at 25 °C [μS·cm−1] 0.1 1.0 5.0

Acidity/Alkalinity pH at 25 °C - - 5.0–7.5

Organics Total Organic Carbon/p.p.b.(μg/l) - - -

Total Solids mg/kg - 1 2Colloids Silica [μg/ml] - - -Bacteria CFU/ml - - -

Contaminant ParameterASTM (D1193-91)

Type I* Type II**

Type III***

Type IV

Ions Resistivity at 25 °C [MΩ·cm] 18 10.0 4.0 0.2

Conductivity at 25 °C [μS·cm−1] 0.056 0.1 0.25 5.0

Acidity/Alkalinity pH at 25 °C - - - 5.0–8.0

Organics Total Organic Carbon/p.p.b.(μg/l) 50 50 200 -

Total Solids mg/kg - - - -Colloids Silica [μg/ml] <2 <3 <500 -Bacteria CFU/ml - - - -

Grade of Water

Resisitivity (M-cm)

TOC (ppb)

Bacteria (CFU/ml)

*Endotoxin (EU/ml) Typical Applications 

Type 1+  18.2  <5  <1  <0.03 GF-AAS, ICP-MS, trace metal detection

Type 1  >18  <10  <10  <0.03

High Perfirmance Liquid Chromatography (HPLC), GC, AAS, immunocytochemistry, mammalian cell culture, plant tissue culture

Type 2+  >10  <50  <10  NAGeneral laboratory applications requiring higher inorganic purity

Type 2  >1  <50  <100  NA

 Feed to ultra pure type 1 systems, feed to clinical analyzers, electrochemistry, sample dilution, media preparation, radioimmunoassay

Type 3  >0.05  <200  <1000  NA

 Feed to ultra pure water type 1 systems, feed to washing machines, dishwashers, autoclaves

Contaminant ParameterNCCLS (1988)

Type I

Type II

Type III

Ions Resistivity at 25 °C [MΩ·cm] >10 >1 >0.1

Conductivity at 25 °C [μS·cm−1] <0.1 <1 <10

Acidity/Alkalinity pH at 25 °C - - 5.0–8.0

Organics Total Organic Carbon/p.p.b.(μg/l) <50 <200 <1000

Total Solids mg/kg 0.1 1 5Colloids Silica [μg/ml] <0.05 <0.1 <1Bacteria CFU/ml <10 <1000 -

Contaminant ParameterPharmacopoeia

EP (20 °C) USP

Ions Resistivity at 25 °C [MΩ·cm] >0.23 >0.77

Conductivity at 25 °C [μS·cm−1] <4.3 <1.3

Acidity/Alkalinity pH at 25 °C - -

Organics Total Organic Carbon/p.p.b.(μg/l) <500 <500

Total Solids mg/kg - -Colloids Silica [μg/ml] - -Bacteria CFU/ml <100 <100