(1) Except as permitted by Sentences (2) and (3), a non-potable water system shall not be connected to a potable water system.
(2) Make-up water may be supplied to the non-potable water system by,
(a) a reduced pressure backflow preventer, or
(b) an air gap.
(3) Where a clothes washer is supplied by a rainwater system and a potable water system, the potable water system shall be protected by dual check valve backflow preventers conforming to CSA B64.6, “Dual Check Valve (DuC) Backflow Preventers” for,
(a) area isolation, and
(b) premise isolation.