Laboratory water purification systems produce high-purity water that meets the specific quality requirements of research, analytical, clinical, and pharmaceutical workflows. Water is the most widely used reagent in any laboratory, and even trace levels of ionic, organic, biological, or particulate contamination can compromise assay results, damage sensitive instrumentation, or introduce systematic error into analytical measurements. Selecting the right water purity grade for each application is as important as selecting the right instrument.
LabRepCo carries Millipore laboratory water purification systems – including the industry-standard Milli-Q series for ultrapure water production – covering Type I ultrapure, Type II pure, and Type III reverse osmosis water. Millipore is the recognized global leader in laboratory water purification, and Milli-Q ultrapure water is the standard reference against which all other water purification systems are measured in research and analytical laboratories worldwide. Contact a LabRepCo specialist at 800-521-0754 to discuss your water purity requirements and identify the right system for your application.
The ASTM International and ISO standards define three grades of laboratory water based on purity, each appropriate for different applications. Understanding which grade your workflow requires is the first step in selecting the right purification system.
| Water Grade | Resistivity | Primary Applications | Millipore Systems |
| Type I (Ultrapure) | 18.2 MOhm-cm | PCR, HPLC, LC-MS, cell culture, molecular biology, sensitive analytical assays, preparation of standards | Milli-Q IQ 7000, Milli-Q Reference, Milli-Q Integral series |
| Type II (Pure) | 1-15 MOhm-cm | General laboratory use, buffer preparation, culture media, reagent preparation, clinical analyzers, feed water for Type I systems | Millipore Elix series |
| Type III (RO Water) | 0.05-1 MOhm-cm | Glassware rinsing and washing, autoclave water, feed water for Type II and Type I systems, general rinsing | Millipore Progard RO |
| Distilled Water | Variable | Classical applications, traditional protocols, teaching laboratories, applications requiring distillation specifically | Laboratory distillation stills |
Modern laboratory water systems combine multiple purification technologies in sequence to achieve the required purity grade. The specific combination determines both the final water quality and the system’s operating cost and maintenance requirements.
Reverse osmosis forces feed water through a semipermeable membrane at pressure, removing up to 99% of dissolved solids, bacteria, and most organic compounds. RO is the primary technology for Type III water production and serves as the pre-treatment stage in Type I and Type II systems, dramatically extending the life of downstream purification components.
Ion exchange resins remove cationic and anionic impurities from water, producing high-resistivity deionized water. Mixed bed deionization – combining cation and anion exchange resins in a single column – produces the highest resistivity water achievable by ion exchange alone. Deionization is the core technology in Type I and Type II systems.
UV lamps operating at 185 nm break down dissolved organic compounds through photochemical oxidation, reducing total organic carbon (TOC) to the sub-ppb levels required for ultrapure Type I water. UV treatment also inactivates bacteria and other microorganisms, preventing biological contamination from proliferating within the purification system. Milli-Q systems combine UV treatment with downstream polishing for consistently low TOC levels.
Ultrafiltration membranes with defined molecular weight cutoffs remove particles, colloids, endotoxins, nucleases, and proteases from purified water. This is particularly important for cell culture and molecular biology applications where trace levels of RNases, DNases, or endotoxins in the water would compromise experimental results. Milli-Q IQ 7000 and Milli-Q Reference systems include ultrafiltration as a final polishing step for ultrapure water production.
| Category | Description | Browse |
| Type 1 Ultrapure Water Systems | Millipore Milli-Q systems producing 18.2 MOhm-cm ultrapure water for PCR, HPLC, LC-MS, cell culture, and sensitive analytical applications. Point-of-use dispensing with online resistivity monitoring. | View All |
| Type 2 Pure Water Systems | Millipore Elix series systems producing 1 to 15 MOhm-cm pure water for general laboratory use, buffer and media preparation, and as feed water for Type I systems. | View All |
| Type 3 Reverse Osmosis Water Systems | Millipore RO systems for glassware washing, autoclave water, and pre-treatment feed water for Type I and Type II systems. | View All |
| Water Distillation Stills | Laboratory distillation stills for producing distilled water through traditional thermal distillation for classical protocols, teaching labs, and applications requiring distillation specifically. | View All |
Using water purity below what your application requires is a common cause of poor assay reproducibility, chromatographic baseline noise, and instrument contamination. Using a higher purity grade than necessary adds cost without benefit. Use the application guide below to confirm the minimum water grade required for your workflow.
| Application | Minimum Water Grade Required |
| PCR and qPCR | Type I ultrapure – RNase and DNase free |
| HPLC and LC-MS mobile phase preparation | Type I ultrapure – low TOC (less than 5 ppb) |
| Cell culture media preparation | Type I ultrapure – low endotoxin, RNase/DNase free |
| Preparation of analytical standards | Type I ultrapure |
| ICP-MS and trace metal analysis | Type I ultrapure – low metal content |
| Buffer preparation and reagent dilution | Type II pure |
| Clinical analyzer and autoanalyzer feed | Type II pure |
| Glassware washing (final rinse) | Type II pure or Type III RO |
| Autoclave water, general rinsing | Type III RO |
| Classical wet chemistry and teaching labs | Distilled or Type III RO |
Type I ultrapure water has 18.2 MOhm-cm resistivity and is required for the most demanding applications including PCR, HPLC, and cell culture where even trace ionic or organic contamination affects results. Type II pure water is suitable for general laboratory use including buffer preparation and clinical analyzers. Type III water is produced by reverse osmosis and is used for glassware washing and as feed water for higher purity systems. Each grade requires progressively more sophisticated purification technology to achieve.
Milli-Q is Millipore’s brand of laboratory water purification systems and is widely regarded as the industry standard for ultrapure Type I water production in research and analytical laboratories. Milli-Q systems use a combination of reverse osmosis, deionization, UV oxidation, and ultrafiltration to produce 18.2 MOhm-cm resistivity water with extremely low levels of organics, endotoxins, and particulates. The Milli-Q name has become synonymous with ultrapure laboratory water in research laboratories worldwide. LabRepCo carries the Milli-Q IQ 7000 and other Millipore water purification systems as an authorized distributor.
Deionized (DI) water has ionic impurities removed through ion exchange resin, producing high-resistivity water suitable for most laboratory applications. Distilled water is produced by boiling water and condensing the steam, removing non-volatile impurities but not all ions or volatile organics. Deionized water generally achieves higher purity for ionic contaminants more efficiently than distillation. Modern ultrapure water systems like Milli-Q combine deionization with reverse osmosis and UV treatment for water purity far exceeding what either distillation or simple deionization alone can achieve.
HPLC and LC-MS applications require Type I ultrapure water with 18.2 MOhm-cm resistivity and extremely low total organic carbon content – typically less than 5 ppb TOC. Using lower purity water in HPLC mobile phase preparation introduces UV-absorbing contaminants that increase baseline noise, affects peak resolution, and can damage column packing and instrument components over time. Millipore Milli-Q systems produce water meeting HPLC-grade purity requirements with online resistivity and TOC monitoring to confirm water quality before use.
Most laboratory water purification systems use multiple technologies in sequence. Reverse osmosis removes up to 99% of dissolved solids by forcing water through a semipermeable membrane. Ion exchange deionization then removes remaining ionic contaminants. UV oxidation at 185 nm breaks down organic compounds and inactivates microorganisms. Ultrafiltration removes particles, endotoxins, and nucleases for the final polishing step. The combination and sequence of these technologies determine the final water purity grade. Millipore systems integrate these technologies with online monitoring of resistivity and TOC to continuously confirm water quality.
Browse our complete laboratory water purification systems selection including Millipore Milli-Q ultrapure, Elix pure, and RO systems, and laboratory distillation stills. Contact LabRepCo at 800-521-0754 for system sizing guidance and to discuss consumable and service requirements for your specific application.
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