Translation guide
In Japanese, 'tap water' is most commonly expressed as 水道水 (suidousui), but in everyday conversation, people often just say 水 (mizu) when the context is clear. There are also more specific terms for drinking water from the tap.
Referring to water that comes from a faucet or tap, typically in a home or building.
The standard, neutral term for tap water. Used in both spoken and written contexts.
この地域の水道水は飲めますか？
Is the tap water in this area safe to drink?
水道水で顔を洗った。
I washed my face with tap water.
In casual conversation, simply saying 水 (water) often implies tap water, especially when at home or in a restaurant. Context makes it clear.
If you need to be specific (e.g., distinguishing from bottled water), use 水道水.
コップに水を入れてください。
Please fill the glass with water (from the tap).
Specifically emphasizing that the water is for drinking and comes from the tap.
Literally 'water from the water supply'. Often used when talking about drinking tap water.
水道の水をそのまま飲んでも大丈夫ですか？
Is it okay to drink tap water as is?
Literally 'water from the faucet'. More colloquial and vivid.
蛇口の水は冷たくておいしい。
The water from the tap is cold and delicious.
Making a distinction between tap water and bottled water.
When contrasting, use 水道水 for tap water and ミネラルウォーター for bottled water.
水道水とミネラルウォーター、どちらが好きですか？
Which do you prefer, tap water or bottled water?
In everyday situations, like asking for water at a restaurant or at home, 水 (mizu) is enough. Adding 水道 (suidou) can sound overly technical unless you need to be specific.