海外でウォシュレットが普及しないのは、海外の水が硬水で
メンテナンスが大変だかららしいぞ！

Washlets don't seem to be spreading to other countries. It seems to be because their water is hard, and maintenance is a real problem.
"Washlet":https://en.wikipedia.org/wiki/Washlet is the trademarked term for toilets with water jet features.