Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Mixing distilled and tap water

Learn more physics!

Most recent answer: 11/24/2014
If you pour some non-distilled water, like mineral water or alkaline water, into distilled water, will that make it non-distilled? I use a water distiller to treat my drinking water but read it's not good to drink distilled water, at least, in the long term because it can cause health problems, due to removing minerals from your body. I've read distilled water has nothing in it but H2O, so if you add water that has stuff in it, like salts, minerals, etc, would that make it no longer distilled water?
- Rory (age 30)
Memphis, TN, U.S.A

Mixing some tap water (say X %) into some distilled water just gives you water with X% as many solutes as the tap water had. There's no trick to it. If the tap water had some calcium salts, for example, and you make a solution with 40% tap water, it will have 40% as high a calcium salt concentration as the tap water had. It's no longer distilled water.

There is, as you've heard, a little bit of evidence that tap water has some protective effect against some cardiovascular disease. () That is apparently due to some trace elements dissolved in the water- maybe lithium or vanadium according to that linked article. If you want to get that suspected benefit from those trace elements, you have a couple of options. You might take a supplement containing them. Or you could just switch to tap water. If you're avoiding tap water because of some contaminant (pesticide?...) then perhaps it would be best just to use a good charcoal filter rather than distilling it. Here's a nice introduction to various types of filters: . Charcoal ("activated carbon") remove many contaminants but leaves many simple salts. I'm not sure whether it removes the ions suspected of having good cardiovascular effects. Since it is ineffective for lithium poisoning, , I suspect that it won't take much of the lithium out of the water.

Mike W.

(published on 11/24/2014)

Follow-up on this answer.