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 |
| 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 |
** 0.22 µ filtration included
CLSI: formerly known as NCCLS (US National Committee for Clinical Laboratory Standards)
CLRW: Clinical Laboratory Reagent Water
| 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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