What's allowed in a treatment system is based on the plumbing code. There's a national plumbing code of Canada that establishes things, but then each province and in some cases a municipality will adopt their own version of the plumbing code. We can tell until when lead could be used in pipes, for example, but we don't know after that when it would have been adopted by the provinces. The dates are a bit too hard to come by and it really depends on the province.
On June 6th, 2017. See this statement in context.