How to say "sewage" in Japanese

• 汚水おすいCommon
  nounSewage as filthy water in itself: dirty or polluted water of any kind, such as foul water discharged from a factory or kitchen. It describes the water's filthiness rather than a drainage system.
  そして汚水おすいを流ながすために地下ちかに下水道げすいどうを持もっていた。↗

  The house has pipes under the ground to carry dirty water away.
• 下水げすいJLPT N2approx.Common
  nounSewage as drained waste water: what has gone down the drains and flows off through the sewers. It can also refer specifically to black water, the waste from toilets.

For sewage as foul, dirty water in itself use 汚水; for sewage as the waste water that drains away through sewers — including black water from toilets — use 下水.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 汚水おすいfilthy water
• 下水げすいsewage