wastewater n.

c. 1300, of land, "desolate, uncultivated," from Anglo-French and Old North French waste (Old French gaste), from Latin vastus "empty, desolate," from PIE *wasto-, extended suffixed form of root *eue- "to leave, abandon, give out." From c. 1400 as "superfluous, excess;" 1670s as "unfit for use." Waste-paper attested from 1580s.

Old English wæter, from Proto-Germanic *watr- (source also of Old Saxon watar, Old Frisian wetir, Dutch water, Old High German wazzar, German Wasser, Old Norse vatn, Gothic wato "water"), from PIE *wod-or, suffixed form of root *wed- (1) "water; wet."

To keep (one's) head above water in the figurative sense is recorded from 1742. Water cooler is recorded from 1846; water polo from 1884; water torture from 1928. Linguists believe PIE had two root words for water: *ap- and *wed-. The first (preserved in Sanskrit apah as well as Punjab and julep) was "animate," referring to water as a living force; the latter referred to it as an inanimate substance. The same probably was true of fire (n.).