how long will opened distilled water last?

I had to buy a gallon of distilled water to use 6 Tbps... how long will it last? I rarely make cheese, so not sure if I should bother keeping it or not.

Distilled water should be darn near 7 pH. That's pretty acidic as far as water is concerned. Probably too acidic for it to "go bad."

Use it to make up some star san.

_

Nateo said:

Distilled water should be darn near 7 pH. That's pretty acidic as far as water is concerned. Probably too acidic for it to "go bad."

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Distilled water IS right at 7pH but that is neutral, not acidic. As for "keeping" it, at 89 cents a gallon what's the point? +1 on mixing up some Starsan...

Mals

Malstorme said:

Distilled water IS right at 7pH but that is neutral, not acidic. As for "keeping" it, at 89 cents a gallon what's the point? +1 on mixing up some Starsan...

Mals

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If the distilled water is exposed to the atmosphere, then the CO2 present in the atmosphere will turn into carbonic acid in the water as it's absorbed. The pH of the solution will eventually end up around 5.2 if left alone long enough.

Distilled and RO water is corrosive. Generally, drinking water, if treated by municipal plants, has a pH of 7.5-8, in order to reduce corrosion of the city's pipes. That's why I said it's "pretty acidic" compared to normal municipal drinking water.

I've got some that's over 4 billion years old, and it's still good.