Well, the easy way to do this is if we have legacy contaminants for which we have clear guidelines. Then it's easy. We measure how much is in the drinking water and if we are above or below the guideline. Then it's clear.
In the case of something that's not regulated, it's a lot more complex and difficult, but once you have a recommendation from Health Canada that has all the required experts who looked at the issue, then you can compare your data to what is recommended by Health Canada. That's if you're looking just at drinking water. Of course, if you want to transfer drinking water, then it's a question that's a lot more complicated: Is it safe to have a garden and grow your own vegetables if you'll be using that water?
If you're comparing drinking water to something where some official body has made that level, then it's relatively straightforward.