As mentioned above, the Japanese public bath is one area where the uninitiated can upset regular customers by not following correct bathing etiquette designed to respect others. In particular; not washing before bathing, introducing soap into the bath water and horseplay. Sent˘ commonly display a poster describing bathing etiquette and procedures in Japanese or occasionally in other languages for international customers.
Some ports in Hokkaid˘, frequently used by the Russian fishing fleet had problems with drunken Russian sailors misbehaving in the bath. Subsequently, a few bath houses chose not to allow foreign customers at all.
Some public baths have signs refusing entry for people with tattoos. However, one may be allowed in if the tattoos are not too obvious. If one ventures to a public bathing place that is publicly owned, this should not present a problem as they have a duty to let all tax-paying citizens in. The original reason behind the ban was to keep out the yakuza (officially called the "violence groups" by the police).
Japanese public baths have suffered infrequent outbreaks of dangerous legionella bacteria. In order to prevent such problems, the sent˘ union adds chlorine to its baths. At the cost of higher levels of chlorine, bacteria outbreaks are practically non-existent at sent˘ facilities of today.