Sonja,
I have been looking for the very information you referenced. Specifically the percent of untreated sewage. Can you point me to sources that discuss this fact. After realizing why the water can't be consumed I'm like, why would I move to Mexico? I would consider somewhere in the 55%. I just need to know where that is. The entire basin that Chapala, Guadalajara are in is totally out. Large corporations have destroyed everything.