The Ontario Building Code | Markings Required
188.8.131.52. Markings Required
(1) Non-potable water piping shall be identified by markings that are permanent, distinct and easily recognized.
(3) A sign containing the words Non-Potable water, Do Not Drinkshall be in letters at least 25 mm high with a 5 mm stroke and posted immediately above a fixture that is permitted to receive non-potable water.