Refers to the system of supplying clean water, or the water itself as provided through pipes. Often used in contrast with 下水 (sewage).
この地域の上水は地下水を利用している。
The water supply in this area uses groundwater.
上水の水質検査が行われた。
A water quality test of the tap water was conducted.
上水 is clean water supplied for drinking and daily use, the direct opposite of 下水, which is used or waste water carried away for disposal.
water supply system; waterworks
Compound of 上 (upper, above) and 水 (water), referring to clean water brought in, as opposed to wastewater (下水).