You know, I lived in Ecuador for 2 years, and I never even thought of that one. I mean, I had taken all the shots and pills and such, and was always seeing the advisories to not drink the water, but I never thought twice about it and just did my normal shower and shave routine. I've been back 7 years now and haven't been sick with anything. Who knows, I could be lucky though.
What I would suggest is talking to your doctor, or travel doctor - if you have any of those travel clinics there that specialize in all the shots and meds needed depending on where you're traveling to. They would probably be able to answer that best.
Anyway, good luck with that!