noun, noun or participle which takes 'suru'
leaving bathwater for later use (e.g., laundry)
Refers to the practice of not draining the bathtub after bathing, so the water can be reused for washing clothes or other purposes. Often used in contexts of water conservation.
残し湯で洗濯すると水道代が節約できる。
You can save on water bills by doing laundry with leftover bathwater.
母はいつも残し湯
My mother always uses the leftover bathwater for laundry.