I don't think anyone can claim to know for sure. The future is murky. What does seem clear is that this will drastically affect weather patterns that South Asia

I don't think anyone can claim to know for sure. The future is murky. What does seem clear is that this will drastically affect weather patterns that South Asian civilization has relied in for millenia, and will definitely stress already compromised water resources, which I would imagine will cause a significant refugee crisis. I'm not entirely sure where those refugees would even go, China? I'm not sure on what you mean on the feces contamination question. Water contaminated by human waste is not safe without treatment for consumption in the slightest.