Bathrooms are not designed the same way everywhere in the world.
In countries such as the United States and the United Kingdom, it is common to use the shower only inside a bathtub or shower enclosure, with a curtain or glass panel keeping the water from spreading across the rest of the room.
In some parts of Northern Europe and Asia, however, there are also wet rooms, where the entire bathing space is waterproofed and a drain is built into the floor.
So the idea of a room that can get completely wet is not unique to Japan.
Why, then, is this kind of bathing space so common in Japanese homes?
The main reason is that in Japan, people usually wash their bodies and hair outside the bathtub.
A typical Japanese bathing room has a washing area next to the tub. People use the shower there to wash themselves, and then get into the bathtub after they are clean.
In other words, the bathtub is not mainly a place for washing. It is more a place to soak in hot water and warm up after washing.
In the washing area, there is no need to worry about shower water running across the floor. Some people sit on a small bath stool while washing themselves, while others stand to wash their hair. When bathing children, people may use much of the space around the tub.
Naturally, not only shower water but also soap and shampoo rinse across the floor. Water may splash onto the walls or the outside of the bathtub as well.
For that reason, Japanese bathing rooms are built with the expectation that both the floor and walls will get wet. The floor also has a drain so the water can flow away.
If you are used to bathrooms where water is kept inside the bathtub or shower enclosure, you may feel uneasy the first time you use a Japanese bathroom and wonder, “Is it really okay to let this much water run across the floor?”
In a typical Japanese home, however, that is completely normal. The whole bathing area, including the washing space, is designed as a place where water is used.
Of course, this does not mean that the changing area or washroom outside the bathing room can also be soaked. The waterproof area is the bathing room itself.
Japanese bathing rooms are designed this way because washing happens outside the tub, so the entire bathing area, not just the bathtub, needs to handle water.
References
- TOTO, “What Is a Unit Bath?”
- LIXIL, “Bathrooms and Unit Baths”
