To see a pool of water in your dream indicates that you need to acknowledge and understand your feelings. It is time to dive in and deal with those emotions. Alternatively, a pool indicates your desire to be cleansed. You need to wash away the past.
If you have a dream of a dark and/murky pool, then it suggests that you are wallowing in some negative emotions. Alternatively, a dark pool implies that your thinking or judgment is being clouded by your emotions. You are not thinking rationally.
To dream that you are playing or shooting pool represents your competitive nature. You need to learn to win or lose gracefully. Alternatively, shooting pool means that you need to concentrate harder on a problem in your waking life.