What is a drinking-water system?
On this site, almost everything hangs off the word “system.” Here is what it means in plain language.
A system is a public file
Ontario tracks regulated water supplies: a town plant and pipes, a small supply, or the water serving one school or child-care building. Each has its own history of tests and follow-up in the open data — and its own page here.
Each also has a long official ID number. You do not need it to use the site; it lives in the collapsed technical section if you ever need it.
Not the same as your address
Records name a place (a city or town), not a street-by-street map of who gets which supply. Searching your city shows systems linked to that area — a strong hint, not proof for your door. Your city can confirm which system serves you.
Why one place can list many
A city may have supply plants, distribution systems, plus separate school and child-care building files. That is normal — and why a city page is a list, not a single grade.