How To Select The Right Water Purity For Your Lab Applications

12 Jun 2026

Pure Water Is Used Almost Everywhere In The Lab

Water is used almost everywhere in the lab, from being a key reagent in your day-to-day experiments, tests, and assays, to performing those "behind the scenes" functions like autoclaving, glassware cleaning, media preparation, and water bath setup. But not all lab water is created equal. Different techniques demand different levels of purity, and using the wrong grade can introduce ions, organics, or microbial contaminants that bias results, damage instruments, or invalidate an entire run.

Most lab water falls into three grades defined by ASTM D1193 and ISO 3696. Type I (ultrapure) water is required for the most sensitive applications (HPLC, UHPLC, LC-MS, GC-MS, ICP-MS, ICP-OES, atomic absorption spectroscopy, cell and tissue culture, PCR, qPCR, and next-generation sequencing) where trace contaminants would interfere with detection or biological activity. Type II (pure) water is the right choice for buffer preparation, ELISA and immunochemistry workflows, microbiology, electrochemistry, and spectrophotometry. Type III (RO) water is sufficient for glassware washing, autoclave feed, and media prep, and is also commonly used as feedwater for Type I polishing systems. Clinical chemistry analyzers require CLRW-grade water.

Knowing exactly which type of water purity your particular application requires can take time to go away and research — time that could be better spent at the bench. To help you make the most of your valuable time, we've assembled this quick reference table enabling you to easily match your application with the required water quality.

And for more information about the different types of water, check out this guide here too.

Check Out Our Quick Reference Guide To Match Your Laboratory Application And Water Purity

Technique	Application sensitivity required	Resistivity (MΩ-cm)*	TOC (ppb)	Filter (μm)	Bacteria (CFU/ml)	Endotoxins (EU/ml)	Nucleases	Water grade	Water type
Feed to still	Low	>0.05	<500	NA	NA	NA	NA	Primary	III
Feed to ultra pure water system	General	>0.05	<50	NA	NA	NA	NA	Primary	II+
Feed to ultra pure water system	High	>1	<10	<0.2	<1	NA	NA	Ultra pure	I
General chemistry	General	>1	<50	<0.2	<10	NA	NA	General lab	II+
Glassware washing	General	>1	<50	<0.2	<10	NA	NA	General lab	II+
Glassware washing	High	>18	<10	<0.2	<1	NA	NA	Ultra pure	I
Media preparation	General	>1	<50	<0.2	<1	NA	NA	General lab	II+
Solution preparation and dilutions	General	>1	<50	<0.2	<1	NA	NA	General lab	II+
Solution preparation and dilutions	High	>18	<10	<0.2	<1	NA	NA	Ultra pure	I
Steam generation	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Bacterial cell culture	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Clinical biochemistry	USP/EP	>2	<500	<0.2	<1	NA	NA	General lab	I
Clinical biochemistry	CLSI	>10	<500	<0.2	<1	NA	NA	General lab	I
Electrophoresis	High	>18	<10	UF	<1	<0.005	ND	Apyrogenic Ultra pure	I
Electrophysiology	General	>1	<50	<0.2	<1	NA	NA	General lab	I
ELISA	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Endotoxin analysis	Standard	>1	<50	<0.2	<1	<0.05	NA	Apyrogenic General lab	I
Endotoxin analysis	High	>18	<10	UF	<1	<0.002	ND	Apyrogenic Ultra pure	I
Histology	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Hydroponics	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Immunocytochemistry	High	>18	<10	UF	<1	<0.002	ND	Apyrogenic Ultra pure	I
Mammalian cell culture	High	>18	<10	UF	<1	<0.002	ND	Apyrogenic Ultra pure	I
Microbiological analysis	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Molecular biology	High	>18	<10	UF	<1	<0.002	ND	Apyrogenic Ultra pure	I
Monoclonal antibody research	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Monoclonal antibody research	High	>18	<10	UF	<1	<0.002	ND	Ultra pure	I
Plant tissue culture	High	>18	<10	UF	<1	<0.002	ND	Apyrogenic Ultra pure	I
Radioimmunoassay	General	>1	<50	<0.2	<1	NA	NA	General lab	I
Electrochemistry	General	>5	<50	<0.2	NA	NA	NA	General lab	II
Electrochemistry	High	>18	<10	<0.2	<1	NA	NA	Ultra pure	I
Flame-AAS	General	>5	<500	<0.2	NA	NA	NA	General lab	II
GC-MS	High	>18	<3	<0.2	<1	NA	NA	Ultra pure	I
GF-AAS	High	18.2	<10	<0.2	<10	NA	NA	Ultra pure	I+
HPLC	General	>1	<50	<0.2	<1	NA	NA	General lab	I
HPLC	High	>18	<3	<0.2	<1	NA	NA	Ultra pure	I
ICP-AES	General	>5	<50	<0.2	NA	NA	NA	General lab	II
ICP-AES	High	>18	<10	<0.2	<1	NA	NA	Ultrapure	I
ICP-MS	General	>10	<50	<0.2	<10	NA	NA	General lab	II+
ICP-MS	High	18.2	<10	<0.2	<1	NA	NA	Ultra pure	I
Ion chromatography	General	>5	<50	<0.2	<10	NA	NA	General lab	II+
Ion chromatography	High	18.2	<10	<0.2	<1	NA	NA	Ultrapure	I
Solid phase extraction	General	>1	<50	<0.2	<10	NA	NA	General lab	II+
Solid phase extraction	High	>18	<3	<0.2	<1	NA	NA	Ultra pure	I
Spectrophotometry	General	>1	<50	<0.2	<10	NA	NA	General lab	II+
Spectrophotometry	High	>18	<10	<0.2	<1	NA	NA	Ultra pure	I+
TOC analsys	General	>1	<50	<0.2	<10	NA	NA	General lab	II+
TOC analsys	High	>18	<3	<0.2	<1	NA	NA	Ultra pure	I+
Trace metal detection	General	>5	<50	<0.2	<10	NA	NA	General lab	II+
Trace metal detection	High	18.2	<10	<0.2	<1	NA	NA	Ultra pure	I+

Don’t see your application listed?

Contact a Lab Water Specialist at one of our Approved Business Partners for assistance - see below.

Find an Approved Partner

Find the right ELGA LabWater product for your application needs

PURELAB® Quest

The only purifier on the market that dispenses all 3 types of science ready water from a compact, economical, and easy to use system! - Type 1, 2, and 3 Water

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PURELAB® Chorus 2

When Type 2 water is all you need, then PURELAB Chorus 2 (RO/DI) is the reliable and flexible solution, providing Type 2 water at 10 M.cm, for needs between 10 and 480 liters per day.

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PURELAB® Chorus 3

The PURELAB Chorus 3 is a modular, Type 3 water purification system with high-capacity storage for general laboratory applications. Ideal for autoclaves, glasswashers, and buffer preparation, where consistent, reliable water is essential.

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FAQs

What type of water do I need for HPLC?: HPLC requires Type I ultrapure water to avoid contaminant interference that can compromise separation and quantification. ELGA's ultrapure water meets 18.2 MΩ·cm resistivity at 25 °C, TOC <10 ppb, and bacterial counts <1 CFU/mL, ensuring the purity needed to protect chromatographic accuracy and reproducibility. PURELAB Chorus 1, flex, and Quest systems are designed for HPLC, LC-MS, and GC-MS workflows. Find the right water purification system for your application or speak to an expert.
What water purity is required for cell and tissue culture?: Mammalian cell and tissue culture requires Type I ultrapure water with bacterial endotoxins below 0.03 EU/mL and undetectable levels of nucleases and proteases. Trace contaminants can inhibit cell growth, alter gene expression, and compromise reproducibility between passages. ELGA's ultrapure systems are designed for mammalian cell culture, protecting cell viability and experimental reproducibility from passage to passage. Find the right water purification system for your application or speak to an expert.
What type of water should I use for PCR and molecular biology?: PCR and molecular biology applications typically require Type I ultrapure water free of nucleases, proteases, and endotoxins, since even trace contamination can degrade nucleic acids or inhibit amplification. ELGA's ultrapure water delivers 18.2 MΩ·cm resistivity at 25 °C, TOC <10 ppb, and undetectable levels of DNases and RNases. Find the right water purification system for your application or speak to an expert.
Can I use Type II water instead of Type I?: Type II water is not a substitute for Type I in applications where trace contaminants affect results, such as HPLC, LC-MS, PCR, or cell culture. Using Type II water in place of Type I increases the risk of background interference, baseline drift, and compromised reproducibility. Type II is suitable for less sensitive applications, including buffer preparation, microbiological analysis, electrochemistry, and spectrophotometry.
What happens if I use water that isn't pure enough for my application?: Using water below the required purity grade puts your results at risk. Contaminants can cause baseline drift, ghost peaks, failed reactions, impaired cell growth, and inconsistent data across runs, leading to wasted reagents, samples, consumables, and time. Matching water purity to the application is the simplest way to protect data integrity. Find the right water purification system for your application or speak to an expert.