悪水[akusui] undrinkable water
井戸水[idomizu] well water
一衣帯水[ichiitaisui] (being separated only by a) narrow strip of water
一水[issui] current (of water)
溢水[issui] inundation

飲水量[insuiryou] amount of drinking
飲料水[inryousui] drinking water
烏の行水[karasunogyouzui] quick bath
雲水[unsui] itinerant priest
塩化水素[enkasuiso] hydrogen chloride

介添え[kaizoe] helper
寄添う[yorisou] to get close
後添い[nochizoi] one's second wife
食品添加物[shokuhintenkabutsu] food additive
申し添える[moushisoeru] to add to what has been said

添う[sou] to meet (one's expectations, etc.)
添加[tenka] addition
添加剤[tenkazai] addition agent
添加物[tenkabutsu] addition
添削[tensaku] correction