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

衛生基準[eiseikijun] health standards
下準備[shitajunbi] preliminary arrangements
間接照準射撃[kansetsushoujunshageki] indirect fire
規準化[kijunka] normalization
技術水準[gijutsusuijun] state-of-the-art

公準[koujun] postulate (in math, logic, etc.)
高水準[kousuijun] high level
準える[nazoraeru] to pattern after
準じる[junjiru] to follow