Many people question why their spa will only heat to 104 ºF. Throughout history public bathing was done at higher temperatures. Even today, in Japan, many public bath houses have water up to 115 ºF. Hot tubs & spas in the United States, Canada and most parts of the world have been regulated to obtain a maximum temperature of 104 ºF since 1980.  On Dec 31, 1979, the Consumer Products Safety Commission, CSPC, released .