system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why dose warm/hot water come out of the tap "milky" or foggy white when cold water comes out clear?

Won't let me fix typo :(
gpt
The tap water has gas dissolved in it, much like carbon dioxide in a fizzy drink.

The amount of gas that can be dissolved depends on the temperature and pressure. If you lower the pressure, less gas is soluble so it bubbles out, like opening a soda. Similarly, the lower the temperature, the more gas water can hold, like opening a warm soda vs a cold soda; the warm one will fizz a lot more because the gas is less soluble.

When water comes out of the tap, pressure is released. In cold water, the gases mainly stay dissolved. In hot water, they are less soluble and escape as small bubbles which make the water appear milky until it has settled for a while.

You can detect that the dissolved gas is present in cold water by freezing it. You will notice the center of the ice will have a milky region of small bubbles as the gases are forced to the center during freezing. If you freeze hot water, you will notice a lot less cloudiness in the ice because the heating forced the gas out.