Here below we collected and put together various quality standards for laboratory water with parameter and controls for your quick reference, so far the followings are covered:

• ASTM: American Society for Testing and Materials
• ISO: International Organization for Standardization
• CLSI/NCCLS: Clinical and Laboratory Standards Institute
• USP: United States Pharmacopoeia
• EP: European Pharmacopoeia

ASTM Standards for Laboratory Reagent Water (ASTM D1193-99e1)

Measurement (Unit)	Type I	Type II	Type III	Type IV
Resistivity (MΩ-cm)	> 18	> 1.0	> 4.0	> 0.2 (200KΩ)
Conductivity (µS/cm)	< 0.056	< 1.0	< 0.25	< 5.0
pH at 25˚C	N/A	N/A	N/A	5.0 – 8.0
Total Organic Carbon (TOC) ppb or µg/L	< 50	< 50	< 200	no limit
Sodium (ppb or µg/L)	< 1	< 5	< 10	< 50
Chloride (ppb or µg/L)	< 1	< 5	< 10	< 50
Silica (ppb or µg/L)	< 3	< 3	< 500	no limit

Additional ASTM Sub-Standards for Laboratory Reagent Water

Measurement (Unit)	Type A	Type B	Type C
Heterotrophic Bacteria Count (CFU/ml)	< 1	< 10	< 1000
Endotoxin (units per ml)	< 0.03	< 0.25	not applicable

ISO 3696:1987, Standard Of Water For Analytical Laboratory Use

Parameter	Grade 1	Grade 2	Grade 3
Conductivity µS/cm (temp corrected)	< 0.1	< 1	< 5
pH at 25 °C	N/A	N/A	5.0 – 7.0
Oxidizable matter Oxygen (02) content mg/L	N/A	< 0.08	< 0.4
Absorbance at 254 nm and 1 cm optical path length, absorbance units	< 0.001	< 0.01	N/A
Residue after evaporation on heating at 110 °C mg/kg	N/A	< 1	< 2
Silica (Si02) mg/L	< 0.01	< 0.02	N/A

CLSI-CLRW Guidelines

Contaminant	Parameter and Unit	Type 3	Type 2	Type 1	CLRW
Ions	Resistivity (MΩ-cm)	> 0.05 (50 KΩ)	> 1	> 18	> 10
Organics	Total Organic Carbon (TOC) ppb	< 200	< 50	< 10	< 500
Pyrogens	(Eu/ML)	N/A	N/A	< 0.03	—
Particles	Particles > 0.2 µm (units/mL)	N/A	N/A	< 1 *	**
Colloids	Silica (ppb)	< 1000	< 100	< 10	—
Bacteria	Bacteria (cfu/mL)	< 1000	< 100	< 1	< 10

USP & EP Standards

Properties	USP Purified Water	USP Injection & ‘Highly Purified Water’	EP Sterile & IV Water
Nitrates (ppm)	N/A	N/A	< 0.2
Heavy Metals (ppm)	N/A	N/A	< 0.1
Conductivity (µS/cm)	< 1.3 @ 25 °C	< 1.3 @ 25 °C	< 1.1 @ 20 °C
Total Organic Carbon (TOC) ppb or µg/L	< 500*	< 500*	< 500
Bacteria (guideline)	< 100 cfu/ml	< 10 cfu/100ml	< 10 cfu/100ml
Endotoxin (EU/ml)	N/A	0.25 EU/ml	—

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