There is a Taz on the topic of yoshon (old grain) that says something to the effect of:
כי עיקר חיינו תלוי בשכר
While it's an awesome quote out of context, the basic pretense is that since the water might be toxic where they lived, he permitted the drinking of beer despite the concern of yoshon. I just can't seem to find the actual source, but I know that it exists. Any help with this?