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topic 8221

Deionized vs. Distilled Water


The question of deionized vs. distilled water has come up several times in our Metallurgical Lab. Test/analytical procedures often call for DI, which we do not have readily available. I argue that DI is different than distilled and that you cannot arbitrarily substitute one for the other. Can someone clarify the differences for us?


Jane Olson
- St. Marys, Pennsylvania


Jane - You may want to look at ASTM D1193 [link by ed. to spec at TechStreet] Specification for Reagent Grade Water. It classifies the water into four categories and gives a brief description of each.

Cynthia L. Meade
- Sylvania, Ohio, USA


Hello Jane

We've had a similar discussion, we have DI only and some papers state distilled water.

They are different, they'll be changed minutely by they're processes. I'd happily drink Distilled water, and not touch deionized with a barge pole. In all our work we're simply trying to remove contaminants, and that could be done either way.

There must be some published work comparing the two, I'll have a search, if I find anything I'll post it here.

Ian Brooke
university - Glasgow, Scotland


I have the same question about the difference between DI water and Distilled water and it looks like chemically/analytical there is difference. In my application, I'm only trying to remove contaminants from a polishing machine so they could be interchanged in my process. I am still interested if Ian Brooke finds anything published on DI and Distilled Water differences.

Here an additional website to answer the question about the differences. The difference is in the process to produce the water.

Judy Cox
Agere Systems - Brienigsville, Pennsylvania

Ed. note: That link is now broken


Sorry Judy I forgot. I've now done a search and all I can really find is that distilled and deionized are regarded as different. In one paper they use distilled deionized water, but here they are dealing with leaching the first few angstroms of the surface of feldspar. A biosensor instruction sheet, dictates the use of "glass distilled water" as "Deionized water (even with low conductivities) may contain inhibitors of peroxides and can reduce sensitivity". Neither of these papers dealt with electrochemistry and in my view we add so many mols chemicals to our solutions that I just can't see distilled v's deionized making a significant difference, though I'd keep which ever one you use consistent.


Ian Brooke
- Scotland

June 20, 2008


Both distilled water and DI water remove inorganic ions. Distillation will also boil over volatile impurities (anything that has a vapor/partial pressure) in water into the distilled water. DI process does not remove dissolved organics.

If your requirement is for inorganic ion-free water, you may use either one.

Chat Mohan
- San Diego, California

October 1, 2008

How about in cleaning electronic parts/components, could we use distilled water as replacement for DI water? Also, include possible effects of both if us we use on our cleaning process.

Hope you could answer my query as soon as possible.

Jayce Scott
- Manila, Philippines

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