The water pipe distributes water from water supplies and transports sewage to the sewage systems throughout the city. It is available at the start of the game, after building the first road.
The water pipe is an underground pipeline that carries water to the city and takes sewage out of the city. Water pipes do not affect buildable area, therefore allowing buildings and roads to be built upon. The water pipe creates a twelve radius parameter to allow buildings within the parameter to have proper water and sewage systems.