When he has made her drink the water, then it shall come about, if she has defiled herself and has been unfaithful to her husband, that the water which brings a curse will go into her and cause bitterness, and her abdomen will swell and her thigh will waste away, and the woman will become a curse among her people.Wow, I didn't remember this section. If I were to read this without the priestly references, today we would call this black magic or voodoo or some such. Yet this was the command that God gave to the people.
I do wonder what the disease she would contract from the water was, though that's kind of beside the point. The big deal here is that God would reveal the sin, or clear her of guilt. Trusting to the Lord to prevent a false positive or false negative would be the real act of faith in today's culture, but it would be a miracle God probably brought about daily for them. Still weird to think about.