105 CMR 430.376
Hot Water Temperatures
Where hot water is provided to handwash sinks, lavatories, showers and bathtubs it shall be:
(A) In a quantity and pressure sufficient to satisfy the ordinary use of all plumbing fixtures
which normally need hot water for their proper use and function.
(B) In a temperature range of not less than 110EF (43EC) and not greater than 130EF (54EC)
for fixtures other than a bathtub or shower.
(C) In a temperature range of not less than 110EF (43EC) and not greater than 120EF (48EC)
for a bathtub and shower.