Re: pH of water

Sil Horwitz (silh@iag.net)
Thu, 10 Oct 1996 15:06:26 -0400

At 01:26 PM 961010 +1000, Sandy King wrote: (in part)

>I have checked the pH of the water at my residence many times, both
>withsmall pH tape and with a digital pH meter. It always reads between 4.0
>and 5.5, without any damage to my skin (or so I believe). Sam and I have
>different water suppliers but the source is the same, i.e., the Appalachian
>mountains, so I was not surprised that he reported a reading of 3.5, though
>my readings have never been quite that high (low?).

My point was that any reading below 7.0 is acidic; i.e. a reading of 1
through 6 is acid - the lower the number, the more acid. What Sam said was
that his reading of 3.5 pH was very alkaline, which can't be true as only
readings higher than 7 are alkaline (10 being the most alkaline). Water
having a pH of 4 to 5.5 is mildly acidic, and thus would not be normally
harmful to the skin, though you would need to add more alkali to any
sensitive photographic solution to neutralize the acidity. That's why I use
distilled water for all photo solutions except wash water (our water here,
running through limestone, has a pH running from 7.5 to 8, which is slightly
alkaline, but I don't trust it because the pH can vary).

Beware, the numbers can throw you!

Sil Horwitz, FPSA
Technical Editor, PSA Journal
silh@iag.net