Have they ever had the runs? Giardia can be fatal to puppies and sick dogs.
The danger isn't rainwater. It is stagnant water and running water that has been contaminated. Both are more of a problem in rural and wilderness where there are animals that have been contaminated.
Hmmm, most of my friends' animals (pets) kept at home, medicated, fed "pet food" and "clean" water, tend to be significantly sicker than my outside-kept animals, and always seem to have a short lifespan. They have certainly had the runs more often than my outside-only-"kept" animals.
My cats literally drink stagnant water every single day, algae, bacteria, various protozoa and all. The safety'ism in HN is out of control.
The danger isn't rainwater. It is stagnant water and running water that has been contaminated. Both are more of a problem in rural and wilderness where there are animals that have been contaminated.