I did a bit of digging and it seems that, although potable water standards are established by the Federal government, they are enforced by Provinces. That opens a huge can of worms called the British North America Act, 1867, renamed the Constitution Act, 1982. http://laws-lois.justice.gc.ca/eng/Const/index.html
Sections 91 and 92 specify what powers are divided between Parliament and Provinces respectively. Section 92 (8) says:
92. In each Province the Legislature may exclusively make Laws in relation to Matters coming within the Classes of Subjects next hereinafter enumerated; that is to say,
8. Municipal Institutions in the Province.
I guess that can be taken to read municipal water, which must conform to Federal standards.
As far as potable water aboard ships, the Maritime Occupational Health and Safety Regulations (SOR/2010-120) apply. The relevant section is:
73. (1) Every employer must ensure that employees are provided with potable water for drinking, personal washing and food preparation.
(2) The potable water must
(a) be in sufficient quantity to meet the purposes set out in subsection (1); and
(b) meet the quality guidelines set out in the most recent edition of Guidelines for Canadian Drinking Water Quality, prepared by the Federal-Provincial-Territorial Committee on Drinking Water and published by the Department of Health.
(3) Potable water for drinking must be available at all times for the use of every employee working on the vessel.
So there you are, you just have to know where to look.
As for where to start the rainmaker, I would assume that the Engineers aboard ship are quite competent enough to establish ground rules. (I know, to assume is to make an ass of u and me) I'd never start a flash distiller or ROD in Halifax Harbour or the Lakes, or within 20 miles seaward of the Cabot Strait. (all that industrial sewage streaming down the Gulf of St Lawrence! YUCK!) North Sea would be OK, it's flushed regularly, but I'd keep it shut down in the Med or Baltic. In the pacific, 20 miles from North America, 2 days away from Japan and China, 20 miles from India, avoiding the rivers, shut down in the PG, 10 miles from Africa, Australia and South America (again, avoid the rivers). As a general rule, at least 10 miles from shore and 20 from an estuary outflow.
In any case, make sure the sterilizer is working, whether it's UV or electroysis!
Discourage incest, ban country "music".