GC: n

S: UNICEF – http://www.unicef.org/media/files/wes_tables.pdf (last access: 14 October 2012); WHO – http://www.who.int/water_sanitation_health/publications/aww2.pdf (last access: 7 July 2015).

N: water (n): Middle English, from Old English wæter; akin to Old High German wazzar water, Greek hydōr, Latin unda wave.
coverage (n): mid-15c., “charge for a booth at a fair,” from cover + -age. Reintroduced 1912, American English, in insurance.

S: MW – http://www.merriam-webster.com/dictionary/water (last access: 12 January 2016); OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=coverage (last access: 12 January 2016).

SYN:
S:

CR: water supply