硬水 こうすい Meanings Noun hard water See also: 軟水 (なんすい). Kanji 硬 hard. Read as コウ. 水 water. Read as スイ. Example sentences 貴殿宅の水道水は硬水過ぎます。軟水を使用しましょう。Your tap water is too hard. Get a water softener. Words containing 硬水 永久硬水 (えいきゅうこうすい) permanent hard water Jinuma: Japanese Dictionary · Word lists