To place it in context, the estimate for the city of Chicago is about 300,000, so for Canada 200,000 would be a bit low. If you doubled it to 400,000 or 500,000, maybe you would hit it right.
There is a complexity to it. Some cities, to get lead out, at one point in time removed their side and left the homeowners' side. They had inventory of what they removed, but they didn't have inventory of what the homeowners had, so there is this added burden of some partials that exist across Canada where the city may not have records, as well as the full service line itself. The number is probably greater than 200,000. It may be around half a million; who knows? It's probably in that kind of ballpark, though.