It seems from here both that some types of water are considered too salty to be acceptable for ritual handwashing and that mikvah water is always considered acceptable. I am left wondering what, exactly, are the limits on water for handwashing. Could one wash with:
Very salty water? (--Presumably yes--in some cases--provided that a mikvah is always acceptable. But what if it's not a mikvah?)
(Visibly) dirty water? (Ditto: How dirty can it be if it's not a mikvah?)
Non-water (juice, wine, other liquid)? What percent non-water would it have to be for it halachically to be considered non-water?
Carbonated water (selzer)?
Water containing treyfs?
Water containing chometz during pesach?
Is any temperature of water acceptable?
Are there differences in the above between morning negel vasser and netilas yadayim upon bread? What about washing kohanim?