Interpretation No. 6081 – Hot Water Supply and Temperature Regulation

Manual Reference Section: 6
Applicable Code: BC Plumbing Code (1998), Part 7, Section 7.6
Status: Approved

Background

The Plumbing Officials’ Association of British Columbia issued Interpretation No. 6081 in response to questions about the regulation of hot water temperatures at plumbing fixtures. The enquiry followed reports of installations where water heater output temperatures exceeded safe delivery limits at points of use, raising concerns about scalding risk, particularly in care facilities and residential occupancies.

Subject Matter

The question put to the Association addressed the maximum permissible hot water temperature at fixtures used for bathing and personal hygiene, and whether thermostatic mixing valves were required at individual fixtures or could be installed at a single central point downstream of the water heater.

Ruling

The Association determined that the maximum hot water temperature delivered to any shower or bathing fixture must not exceed 49 degrees Celsius, in accordance with Subsection 7.6.5 of the 1998 BC Plumbing Code. This limit applied at the point of outlet, not at the water heating appliance itself, recognising that water heaters are commonly set to higher storage temperatures to inhibit the growth of Legionella bacteria.

To achieve the required temperature limit at the point of use, a thermostatically controlled mixing valve conforming to CSA B125.3 was required. The ruling permitted either individual fixture-mounted mixing valves or a centralised mixing valve serving a defined group of fixtures, provided that the piping between the centralised valve and the most distant fixture did not produce a temperature drop that would result in unsatisfactory performance or allow delivery temperatures to fluctuate beyond the limits set by the Code.

Where a centralised mixing valve arrangement was selected, the installer was required to verify that the recirculation system, if present, did not cause blending inconsistencies that could affect temperature stability at any fixture in the group served.

Scope of Application

This interpretation applied to new installations and to existing systems undergoing alteration where the hot water distribution piping or temperature control devices were being modified. It did not address the separate requirements for water heater installation, which fell under Part 7.6 provisions related to appliance connections and safety controls.