noun
water change; changing the water
Commonly used for replacing water in aquariums, fish tanks, or similar containers.
金魚の水槽の水換えを週に一度行っている。
I change the water in the goldfish tank once a week.
noun
Refers to cleaning a well, often as a traditional or seasonal task. Related to 井戸替え.
See also: 井戸替え
昔は年末に井戸の水替えをする風習があった。
In the past, there was a custom of cleaning the well at the end of the year.
井戸替え specifically means well cleaning, while 水換え is broader and more commonly used for water changes in tanks.
Compound of 水 (water) and 換え (changing, replacing). The spelling 水替え uses 替える (to replace).