Your puppy isn't picky about where or what he drinks, and that can be a problem. Just because he's lapping up water doesn't mean the water is safe. Standing water can contain dangerous bacteria, as well as parasites that could make their home in your puppy's intestinal tract.
Giardia and coccidia are the two parasites most commonly transmitted to puppies that drink or play in standing water, but Cryptosporidia is also a danger. Such parasites are spread when infected feces releases protozoa in the water and a puppy then drinks the water. Giardia is frequently spread by infected birds as they defecate in standing water and then another animal comes along and consumes it.. Diarrhea and weight loss are the most common symptoms of water-borne parasites, but in severe cases your puppy may also become dehydrated and lethargic.