If you talk to someone in the food preparation world in Japan, they will often talk about the “Dry Method” when it comes to meal preparation. Dry is now the norm in school lunch centers throughout Japan, but that implies that there was once a “wet system” - which indeed there was!
Dry Food Preparation Method
The Dry Method of cooking and preparing is one in which there is no water flowing on the floor and containers are sealed and contained as much as possible. One of the main reasons that the Dry Method is the norm is its effectiveness in preventing bacteria and mold to grow by not creating a humid environment. With no water splashing on the ground, it is also possible to limit the secondary contamination of food-poisoning causing bacteria. Dry heat is also more comfortable and safe for workers to cook in, and therefore improves hygienic results. Lastly, the Dry Method allows facilities to be used longer as there is generally less wear and tear caused by flowing water.
Below are a few visual examples of practices under the wet system and their transition to the dry system. (Via MEXT)
Further Reading: ウェットシステムからドライシステムへ (From the Wet to Dry System) Japanese Language Only