There are many similarities between a bath in the home, a public bath or an authentic geothermally heated hot spring. Just as in the home a public bath can be reasonably private. The bathrooms in most Japanese homes are quite expensive rooms with a shower/faucet, an extra deep tub and a floor area outside the tub with a drain of some sort. North Americans should always explain that their bathrooms do not have a floor drain or be prepared for a puddle on the floor. The water in the tub is circulated and temperature controlled as is the water coming from the shower or faucet.
In the home, the shoes of course are left at the entrance to the house. At a public bath, the shoes are left outside of the bath area. They may be placed in a keyed locker or simply left on the floor. The key for the shoe locker may be exchanged for a key to a larger locker near the shower area where your clothing are stored. In a more rural setting or in a hot spring resort there may be large wicker baskets provided to place your clothing and drying towel.
A large towel for drying oneself afterwards as well as a small elongated towel are either provided, rented or brought from home. Similarly body soap, shampoo and conditioner are frequently supplied, but in cheaper public baths you may be expected to provide these yourself.
After your clothing have been removed you enter the shower area with the small towel. Here you can use the faucet to fill a basin and pour this water on yourself or in some cases such as in the home a dipper can be used to take water from the bath itself. Alternatively the hand held shower head can be used to clean yourself as you sit on a small stool.
It is also possible that extras such as toothbrushes, hairbrushes and razors may be provided or you can bring these yourself.
And as expected the more you pay, the more you get. You can pay as little as 360¥ or about $4.80 Cdn. at current exchange rates or about 1000¥ in a hotel situation. You might also be willing to be hundreds of dollars for a hot spring resort where everything is provided including a Japanese style room, a dinner banquet as well as a breakfast banquet, sometimes even served in your room. Breakfast may be a Viking or buffet.
Once clean the small towel can be placed on one's head as you enter the bath area. Just remember the bath water is clean water. Normally there is a large common bath in which one sits and there may be a similar bath outdoors which can be used even in the winter. There may be a hot tub or Jacuzzi style tub. Some bath houses such as at a sports club may have a variety of tubs, hot water, water from Israel's dead sea or other mineral water, carbonated water and possibly even cold water. I have also encountered a bath which in one corner had electrified water, which was quite shocking. Public baths may also have wet and/or dry saunas. Feel free to try them all. I have and remember, I don't read the labels very well.
When you are finished bathing, you should probably rinse off the bath water and then use the small towel (hopefully you rinsed the soap out) to sponge off excess water from your body. Then go back to the locker/ changing area and finish drying yourself and put on clean clothes or in the case of a hot spring resort a casual kimono or yukata.
So why have a hot bath. Luxury, true, but traditionally it is an essential step to warming up prior to going to sleep in a cold wintry room. At one time a bath was built on top of an outdoor fire pit which would heat up water in a circular deep metal tub. The metal itself was in direct contact with flames, so you stepped in onto a circular floating wooden floor.
Years ago on my first trip to Japan one of the first Japanese words that was thrown at me, by Yayoi's family was the question whether I wanted to have an "ohuro" or bath.