In theory, whatever bacteria fall into pure water can continue to live for a long time, but they can't make more bacteria. Reproducing and creating new bacteria requires raw materials other than H2O and air.CPAP Lady wrote:The thing with distilled water is the I have only seen gallon jugs of it. As a nurse, it makes me leery to use a jug that has been opened for a week or two even with the cap on. It just seems that it would be a potential breeding ground whereas a small water bottle would only be used for a day or two since both my husband and I use CPAP. OTOH, I am not very religious about washing out the humidifier or equipment
Once you put the cap back on and bacteria stops falling in, the bacteria count shouldn't increase any more. It should be no more nasty in a week than it was when you put the top on.
That assumes the distilled water is close enough to 100% pure that there's not enough of anything the bacteria can feed on. And that you haven't contaminated the water with anything else the bacteria can feed on.
Re: purified or drinking water.
Distilling removes most minerals from the water. Water tastes better with some minerals in it. Purified water for drinking may deliberately leave the "good" minerals in the water. Some purified water has minerals deliberately added back to make it taste better. Good to drink, not so good for humidifier tanks.
The level of minerals in purified drinking water may well be lower than the levels in tap water, so it may still be better.