I don't know.. it seems like every dog I know would rather drink out of a muddy puddle than their clean water bowl.
My dog
Would rather drink the water used to clean chicken shit off the deck than anything else
Would die of thirst rather than drink slightly dusty, dog saliva contaminated water from their bowl. That Must Be Clean! Now, human!!
My dog is obsessed with drinking water from the toilet and will use guests visiting as an opportunity to get into the bathroom.