In brief: “Laboratory water” refers to different water qualities for different analytical and technical purposes. The correct grade depends on the method, not simply on whether water is labelled distilled or pure.
Important quality parameters
| Parameter | What it indicates |
|---|---|
| Conductivity/resistivity | Dissolved ions |
| TOC | Organic carbon compounds |
| Particles | Solid contamination |
| Microbiology | Bacterial or other biological contamination |
Quality according to purpose
Trace analysis, cell culture, HPLC, reagent preparation and basic glassware cleaning can require very different water quality.
Storage is part of quality
Even highly purified water can be re-contaminated by pipes, containers or prolonged storage.
Distilled is not the same as ultrapure
WHO notes that distilled water is free of many nonvolatile compounds but may still contain volatile organic compounds.[1]
FAQ
Is distilled water always laboratory water?
It can be suitable for some uses, but not all.
Is low conductivity enough?
No.
Can ultrapure water be stored?
Only to a limited extent; storage can degrade quality.
Does every lab need ultrapure water?
No. The method determines the required quality.
Conclusion
Good laboratory water is purpose-specific, controlled water quality defined by parameters, maintenance and documented quality control.
