cistern n.

Old English cest "box, coffer, casket," usually large and with a hinged lid, from Proto-Germanic *kista (source also of Old Norse and Old High German kista, Old Frisian, Middle Dutch, German kiste, Dutch kist), an early borrowing from Latin cista "chest, box," from Greek kistē "a box, basket," from PIE *kista "woven container" (Beekes compares Middle Irish cess "basket, causeway of wickerwork, bee-hive," Old Welsh cest).

The meaning of the English word was extended to "thorax, trunk of the body from the neck to the diaphragm" c. 1400, replacing breast (n.) in that sense, on the metaphor of the ribs as a "box" for the heart. The meaning place where public money is kept (common chest, mid-15c.) was extended to "public funds" (1580s). Chest of drawers is from 1670s.

also cess-pool, "cistern or well to receive sediment or filth," 1670s, the first element perhaps an alteration of cistern, or perhaps a shortened form of recess [Klein]; or the whole may be an alteration of suspiral (c. 1400), "drainpipe," from Old French sospiral "a vent, air hole," from sospirer "breathe," from Latin suspirare "breathe deep" [Barnhart]. Meaning extended to "tank at the end of the pipe," which would account for a possible folk-etymology change in final syllable.

Other possible etymologies: Italian cesso "privy" [OED], from Latin secessus "place of retirement" (in Late Latin "privy, drain"); dialectal suspool, from suss, soss "puddle;" or cess "a bog on the banks of a tidal river."