Anything that you can see, which isn't producing its own light is reflecting light from somewhere else; that's how come you can see it. The moon (for instance) is reflecting light from the sun down to earth, which is why you can see it.  Do you have a cat? It is reflecting light from the chandelier … Read more
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Its about 34 feet. There are several smart answers concerning Standard Temperature/Pressure, sea level, relative/absolute pressure etc, but for considering an open head in plumbing needed to add an extra 1 bar to the already existing 1 bar of atmospheric pressure all around us, then the answer is that the head needs to be about … Read more