Wordnet 3.0
NOUN (2)
1. 
 a river and all of its tributaries; 
2. 
 a facility that provides a source of water; 
- Example: "the town debated the purification of the water supply"- Example: "first you have to cut off the water"[syn: water system, water supply, water]
WordNet (r) 3.0 (2006):
water system
    n 1: a river and all of its tributaries
    2: a facility that provides a source of water; "the town debated
       the purification of the water supply"; "first you have to cut
       off the water" [syn: water system, water supply, water]