@north,
There have been people who have gone months without breathing. During that time they were hooked up to a machine that supplied them with oxygen. But they couldn't survive without the machine, because they weren't breathing.
I am not arguing against the meaning of the truths you offer, I am simply trying to show that any truth can be questioned and modified.
And what do you mean "water is a fact"?
Just the concept in itself isn't particularly meaningful. Are you talking about the mix of oxygen and hydrogen? Rain? Are you thirsty?
How do you percieve water? In a number of different ways. More ways that you can think of on the go, and I am betting you even have a few ways to understand water that have no corresponding perception of the actual thing behind it. Just a theory about chemical composition of elements, for instance.
I do not mean to be condescending, but perhaps you could benefit from establishing to yourself with greater clarity the differences between fact and truth? It is a tricky distinction, worthy of philosophic effort. I still get confused at times, and have to doublecheck my references.
And I am not certain that there are no contexts in which it would be more meaningful to think of the sky in other terms that it's color. Situations where the truth "the sky is blue" holds little or no practical value because there is another truth that is of greater meaning in the relevant context.