- water system - a river and all of its tributaries
--1 is a kind of system, scheme
--1 has part: river- water system, water supply, water - facility that provides a source of water; "the town debated the purification of the water supply"; "first you have to cut off the water"
--2 is a kind of facility, installation
--2 is a part of infrastructure, base
--2 has parts: reservoir, artificial lake; water main - water system, water supply, water - facility that provides a source of water; "the town debated the purification of the water supply"; "first you have to cut off the water"