# pH of distilled water



## Tomagorn (Apr 5, 2013)

I used to know a thing or two about water chemistry, but I'm getting dumber with age. Can someone explain to me why distilled water is acidic (pH 6.0 or less)? I'm not complaining about it because I use distilled water and a neutral buffer to offset the high pH (8.6) of my tap water. I'm just confused about why this occurs.


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## b3w4r3 (Dec 14, 2012)

CO2 from the air causes the ph to lower as there are no buffers.


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## Tomagorn (Apr 5, 2013)

Hmmmm. That raises the question of how pure the air is during the distillation process. Around here the air also contains traces of NOx and SOx.


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## b3w4r3 (Dec 14, 2012)

If the water is circulated before using those chemicals will off gas, and it will reach equilibrium with the surrounding air.


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