水
みず
mizu
= water (cold or room-temperature water; as distinct from hot water)
水 (mizu) means water — but in Japanese, the word specifically implies cold or room-temperature water, as distinct from お湯 (oyu — hot water). This distinction is fundamental: when a restaurant brings you water in Japan, it’s 水 (mizu); when a bath is drawn, it’s お湯 (oyu). Understanding when to use mizu versus oyu is one of the first practical distinctions Japanese learners encounter.
Mizu (水) is the general word for water, particularly cold or room-temperature water. Key phrases: お水をください (o-mizu wo kudasai — please give me water, at a restaurant), 水道水 (suidou-sui — tap water), ミネラルウォーター (mineraru wootaa — mineral water), 水を飲む (mizu wo nomu — to drink water), 水を流す (mizu wo nagasu — to run/flush water). Contrast: お湯 (oyu — hot water for bathing, cooking, tea), 冷水 (reisui — cold water, formal/written term). Compounds: 洪水 (kouzui — flood), 水泳 (suiei — swimming), 水曜日 (suiyoubi — Wednesday, literally ‘water day’).
The mizu/oyu distinction is practically important. In restaurants, asking for 水 (mizu) means you want cold water; お湯 (oyu) would mean hot water for tea or instant noodles. At a Japanese onsen or sento (public bath), the separate cold water tap is 水 (mizu) and the main hot bath is お湯 (oyu). In cooking, when a recipe says 水 (mizu), it means cold water; when it says お湯 (oyu), it means boiling or hot water. Water temperature is linguistically significant in Japanese in a way it isn’t in English.
水 (mizu/sui) is one of the most ancient and fundamental kanji — a pictograph of a stream with flowing water. It appears in countless compounds: 水道 (suidou — water supply/plumbing), 海水 (kaisui — seawater), 淡水 (tansui — fresh water), 水分 (suibun — moisture, water content), 水力 (suiryoku — water power). As one of the five classical elements (五行, gogyou) in East Asian philosophy: 木 (wood), 火 (fire), 土 (earth), 金 (metal), 水 (water).
Everyday use
お水をいただけますか？少し喉が渇いてしまって。
O-mizu wo itadakemasu ka? Sukoshi nodo ga kawaite shimatte.
Could I have some water? I’m a bit thirsty.
Casual / Social Media
今日15km走ったから水2リットル飲んだ それでもまだ足りない感じがする
Kyou 15km hashitta kara mizu 2 rittoru nonda Sore demo mada tarinai kanji ga suru
I ran 15km today so I drank 2 liters of water. It still doesn’t feel like enough
Formal / Cultural context
日本語における「水」と「お湯」の語彙的区別は、水温という物理的属性が社会的使用文脈において意味的差異を生む典型例である。英語のwaterが温度を中立的に包括するのに対し、日本語は常温・冷水を「水」、加熱水を「お湯」として語彙的に分化させており、日常生活における水の機能的用途（飲料・入浴・調理）に対応した認知的カテゴリー化を示している。
Nihongo ni okeru ‘mizu’ to ‘oyu’ no goi-teki kubetsu wa, suion to iu butsuri-teki zokusei ga shakai-teki shiyou bunmyaku ni oite imi-teki saiga wo umu tenkei-rei de aru. Eigo no water ga ondo wo chuuritsu-teki ni houkatsu suru no ni taishi, Nihongo wa jooon reisui wo ‘mizu’, kanestu-sui wo ‘oyu’ toshite goi-teki ni bunka sasete ori, nichijou seikatsu ni okeru mizu no kinouteki yoto (inryou nyuuyoku chouori) ni taiou shita ninchi-teki kategorika wo shimeshite iru.
The lexical distinction between ‘mizu’ and ‘oyu’ in Japanese is a typical example of a physical attribute (water temperature) creating semantic differences in social usage contexts. While English ‘water’ neutrally encompasses all temperatures, Japanese lexically differentiates room-temperature/cold water as ‘mizu’ and heated water as ‘oyu,’ reflecting cognitive categorization corresponding to the functional uses of water in daily life (drinking, bathing, cooking).
Water has profound cultural significance in Japan beyond daily utility. 清水 (shimizu — clear, pure water) appears throughout Japanese place names, reflecting historical importance of clean water sources. 水 appears in many traditional arts: 水墨画 (suibokuga — ink wash painting), 水引 (mizuhiki — decorative knotted cord for gift wrapping), 水無月 (minazuki — June, literally ‘waterless month’ — the old name). The summer festival season features 水遊び (mizu-asobi — water play), and children playing with water is an iconic summer image in Japanese culture.
Japan’s tap water (水道水, suidou-sui) is considered among the safest and cleanest in the world — one of few countries where tap water is routinely drunk without filtration. This is a source of quiet national pride: foreign visitors are often surprised to learn that the water they’re handed at Japanese restaurants is simply tap water, indistinguishable in safety from bottled water. The high quality of Japanese municipal water systems is the result of extensive post-war infrastructure investment and ongoing maintenance standards.
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