軟水(なんすい)

A compound of 軟(なん) (soft) and 水(すい) (water). Japan's tap water is predominantly soft water due to the country's geology — short, steep rivers don't allow water to absorb many minerals. This is often discussed in contexts like cooking (soft water brings out the flavor of Japanese tea and dashi), skincare, and when comparing water quality with other countries.

The WHO defines soft water as having less than 120 mg/L of calcium carbonate.

Common collocations

• 軟水(なんすい)と硬水(こうすい): soft water and hard water
• 軟水(なんすい)で淹(い)れる: to brew with soft water
• 軟水(なんすい)に向(む)く: to be suited for soft water
• 軟水(なんすい)の地域(ちいき): soft water region

Similar words

• 硬水(こうすい): hard water — water with high mineral content, common in Europe
• ミネラルウォーター: mineral water — bottled water, which may be soft or hard
• 天然水(てんねんすい): natural water — spring or groundwater, often sold bottled