Bottled water, tap water, river water – What is best on the Camino de Santiago?

Water bottle on the Camino de Santiago

The question was:

probably a silly question but here goes…
I presume there are plenty of places to buy water on the camino?
But…
what is the tap water like?
What is the river water like?
what are the best tablets to dose water (if suspect) with?

Read all the good advice on Water on the Camino de Santiago here.