When did Private Baths become prevalent in Japan? -

I am doing some research, on Japan in the decade just prior to the Meiji Restoration: Particularly 1855-63. I wish to know at what era it became common for homes to have private baths. I am aware that sento are a common feature of this era of Japan, however I wonder if it would be anachronistic to depict an artisan (blacksmith) level home as having a private bath. If one did, what form would this private bath take.

Rich people had private bath in Edo era. Public bath (today s sento) bloomed in this era as well. Probably most common people went to the public bath. However, they also hold small bathing tub like following pics. http://upload.wikimedia.org/wikipedia/co... Some people liked Goemon-buro. Probably artisan were holding this kind of bath. Because they were dirty after their work and some people needed private bath. And I think the time that private bath spreaded nation widely was in 1960s, after the Tokyo Olympics.