When I was little, I asked my mom what the hole at the top of the bathroom sink was. (the overflow protection drain hole)
She told me that was for the water company to watch to make sure I wasn't using too much water. Sounded true to me at the time!
A childhood belief about bathrooms

others believed things like this
- that bathroom tap water was recycled "potty" water from the toliet. — livingdeadgirl
- how many us believed you would go down the drain with the bath water? I did!— Amy
- I used to think that trolls lived in my shower drain and showered with my dirty water— Troll bather
- I used to believe that if you dig a hole in the ground and put pepper in the hole, the ground would sneeze.— Cookie
- I asked my father what holy water was. He told me it was the priest's bathwater. — Gwen
- I thought that hydrogen was pure water (since I knew hydro- meant water) and H2O was impure some how— Hexetic