6. The maximum water level in a bath is seven inches.

Reason: That’s how Queen Elizabeth II wanted it.
Exception: It’s likely that other Royals have different tastes.
Queen Elizabeth loved taking a morning bath to get ready for the day, but she had strict rules about the depth of the water in the bath. Not only did the water in the bath need to be precisely seven inches deep, but the temperature had to be just right.
The maximum water level in a bathtub is seven inches. ©New Africa/Shutterstock
To ensure that no shortcuts were taken, the water was consistently measured. When waiting for her bath to be drawn in the adjacent bathroom, Queen Elizabeth enjoyed sipping a cup of Earl Grey tea and listening to Radio BBC 4, according to Express.