The term 'PIPE WATER' can be solved by the four-letter word 'BONG'. A BONG is a type of water pipe used for smoking cannabis, tobacco, or other substances. It is typically made of glass, ceramic, or plastic and has a bowl, stem, and water chamber. The smoke passes through the water chamber, cooling it before inhalation. Bongs are popular among smokers due to their smoothness and filtration of particulates.