An upscale inn rarely changed the communal bathwater. A probe found 3,700 times the standard limit of legionella bacteria.

The head of an upscale Japanese inn apologized on Tuesday for only changing the water in its hot-spring bath every six months, allowing bacteria to breed 3,700 times over the standard limit.

Local ordinances stipulate a weekly replacement of the water in which guests traditionally soak naked together after taking showers, with men and women bathing separately.

Makoto Yamada, president of the company that operates the nearly 160-year-old inn, said the facility had neglected to keep the water hygienic by using enough chlorine.