お水をください

Using it is very straightforward and beginner-friendly. Just say o-mizu o kudasai clearly to a server or host. The o particle acts like a bridge between the water and the request. You can use it while pointing at a menu or a glass. If you are in a rush, just o-mizu works in a pinch. However, adding kudasai makes you sound much more polite. It shows you have good manners and respect the staff.

Use this when you are sitting at a restaurant table. In Japan, water is usually free and served immediately. If the server forgets, this phrase is your best friend. It is also perfect when visiting a friend's house. If you are thirsty during a business meeting, this works too. It fits perfectly in any neutral social setting. It is a safe, polite, and very clear way to communicate.

Do not use this with very close friends or family. With them, mizu kure or just mizu! is more natural. It might sound a bit stiff in a very casual bar setting. Also, avoid it in extremely formal traditional tea ceremonies. In those rare cases, more humble language is required. But for 95% of your daily life, it is perfect. Don't use it if you want sparkling water specifically. That requires the word tansansui instead!

Japan has some of the cleanest tap water in the world. You can drink it safely almost anywhere you go. In Japanese restaurants, water is usually served for free. This is a core part of Japanese hospitality. They often call it o-hiya in a dining context. The word o-hiya literally means "the cold thing." The o prefix is an honorific used for many items. It shows a sense of gratitude toward the water itself. Japanese culture places high value on nature's gifts. By saying o-mizu, you are being soft and respectful.

You might hear people say o-mizu onegaishimasu instead. Onegaishimasu is slightly more formal than kudasai. It is like saying "I humbly request" versus "Please give." In very casual settings, friends might say mizu choudai. This is very relaxed and sounds quite friendly. If you are at a high-end sushi bar, use o-hiya. If you want a refill, say okawari o kudasai. If you are thirsty for tea, say o-cha o kudasai. The structure remains the same for most drinks. Just swap out the noun at the beginning.