Traditionally built tubs of hand-crafted wood—Japanese cypress, chestnut, cryptomeria, Chinese black pine—are much valued by those who can afford the expense. Most home tubs, however, are made from synthetic materials: tile, enamel, steel, fiber-glass.
Ever energy conscious, the Japanese nowadays heat their bath water as it emerges from the tap, or in the tub itself with coil-type water heaters, rather than storing large quantities of hot water. Because the bather washes away grime before entering tub for the final (and best) soaking stage, water can be saved and reheated for several baths.
In recent decades, the family pecking order for who bathes first each evening has given way to urban realities.
"In earlier times, no one could bathe until the master of the house finished his bath. Rising from the first bath, when the water was hottest and cleanest, he would then be followed by a universally observed hierarchy of bathers. Grandparents came first, followed by eldest son, younger sons, daughters in order of declining age, and finally the wife of the house. Last came retainers and maids or other servants. Nowadays, in the typical small nuclear family the mother may often bathe first—in the late afternoon—so she can get her bath out of the way before setting about preparing dinner. Her children generally bathe next. The father, who often does not return home until well after his wife and children have retired for the night, takes his bath last."
from Furo—The Japanese Bath
by P. Grilli and D. Levy
Adventuresome aliens who poke their way through the household-goods section of Japan's department stores will discover an array of large and small tools of the "art" of the bath. Japanese solutions to the same workaday tasks shared by people everywhere have spawned alternatives in the technology and technique of bathing. Some are as different from their Western counterparts as is judo from brass knuckles.
The ritual begins with a ladling of tub water over the bather, who squats undignified but uncaring next to the tub, or astride a wee stool built so close to the floor that one's legs must be left unceremoniously agape. First, the bather sudses the muskier zones of his or her anatomy, then scrubs and rinses. Next comes an initial soak in the tub to loosen deeper grime for a more thorough assault on the day's accumulations with a raspy wash-cloth, pumice stone and the back-scrubbing help of a friend or neighbor.
A shave, shampoo, and brushing of teeth may follow on the stool before one of the sento's many wall mirrors. The chattering of new arrivals subsides into blissful sighs as bathers sink low into the hot pools after scrubbing skirmishes that leave no bone unchurned.
Reluctant Westerners who think it uncivilized to soak with others should realize that the Japanese think the Western way of soaking solitary in one's sudsy grime to be equally illogical. For bathing to rise above the level of the bowel movement, the dirt should be left outside the tub in the same way shoes and the grime that clings to them are left outside Japanese homes. Hence Japanese bathrooms are built with a drain in the center of the gently sloping tiled floor.