Significant changes to the length of hot water piping to fixtures were made in the 2021 IRC

An addition to Section P2905.3 (Length of Hot Water Piping to Fixtures) of the 2021 International Residential Code states that the code now limits the length of hot water piping serving fixtures. The new section limits the hot water supply line length to 100 feet measured from the source of hot water to the fixtures that require hot water. This provision is similar to existing language in International Plumbing Code (IPC) Section 607.2, except the IPC limits the length to not greater than 50 feet. Hot water supply lines greater than 100 feet waste water (proportional to pipe size) while occupants wait for hot water to reach fixtures for bathing, washing and culinary purposes. Read more here.