I’ve got some 99% Isopropyl I want to dilute to 70, but I don’t have any distilled water atm. I suppose I could wait till I get some, but do the minerals reduce the anti-viral efficacy or the shelf-life of the solution? Thanks.
The short answer is ‘no’
The longer answer is few people would really know, because they haven’t fully tested that particular solution as you want it to perform. So conceivably, there could be some obscure reaction that escapes my understanding where a mineral will react with IPA to alter its ability but those concentrations are pretty small to be not important.
So…
No
If you’re not using the diluted solution to clean glass or other reflective material, you should be fine. The main reason to use diluted water in this case would be to avoid leaving unwanted mineral residue.
Using mineral water will not adversely affect how well it disinfects (as long as you use the correct ratio), nor will it affect shelf-life. The efficacy of the solution will naturally degrade due to alcohol evaporation long before any worries about the mineral water.
You didn’t say whether or not you were shooting for DIY hand sanitizer here, so in case you are, no. Water is not gonna be your friend; you need a mix of aloe vera gel and glycerin so that it’s goopy and doesn’t fry your skin.
Also, you could just 70% of what you would use of the 70% diluted version.