Drinking water often looks cloudy when first taken from a faucet and then it clears up. Why is that?
The cloudy water could be caused by tiny air bubbles in the water similar to the gas bubbles in beer and carbonated soft drinks. After a while, the bubbles rise to the top and are gone. This type of cloudiness occurs more often in the winter, when the drinking water is cold. Another cause of cloudiness in cold water comes from calcium. In certain waters, the nontoxic chemical calcium carbonate will precipitate when it is cold. As it is white, this precipitate can cause the water to look cloudy. In this case, however, the particles settle to the bottom (usually in about 30 minutes) in contrast to the air bubbles discussed above that rise to the top of the water fairly quickly. Water with calcium carbonate precipitate in it is perfectly safe to drink or use for cooking, though it may be unappealing to look at.
