For as long as I can remember, something strange happens in my home when I pour myself a glass of cold tap water. There is a strange accumulation of small air bubbles, so many in fact I would call it a fog even or a mist. After waiting a few minutes, the “mist” all evaporates from my water. But I am left wondering, What exactly is this mist?
I know the water is supposed to be very pure where I live. Yet I don’t know what this mist is, so I usually go to great lengths to avoid consuming it. Does anyone have any ideas what it might be?
It is just air - your tap may have a filter at the nozzle - this breaks up the water stream and air gets caught up in it. It bubbles out or dissolves quickly. It won’t harm you, just contribute to some gas.
Whenever I’ve seen this, it’s been accompanied by a sharp hissing sound when the tap is turned on - in some cases, it only occurs when it’s partially turned on to a specific degree.
I think in the cases I’ve observed, the noise is caused by very rapid vibration of some component, perhaps part of the washer, and that this vibration is sort of splashing tiny air bubbles into the water; they’re so tiny that they take a while to float up to the surface.
Gases such as air are more soluble in cold water than they are in hot. As soon as your cold water comes out of the tap, it starts to warm up, and some of the gases start to come out. If you’ve got a flow restrictor or wierd hissy thing:
in your faucet, that can speed up the process by causing cavitation; tiny bubbles that serve as nucleation sites for gas exchange. If you have a lot of such nucleation sites, you’ll see a haze.
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