Help me drink the water in Mexico!

Well, let’s start with Utah first. I have a month before i go on a survival course and will most likely be exposed to water with Giardia in it. Let’s assume for a second that I will at some point drink untreated water and get Giardia. Can I inoculate myself over time with small amounts until it no longer affected me? How long would this take?
I assume I should be able to do this with the water in Mexico as well. How would I go about doing it in theory?