Sorry, didn't see the rest of your post. Pond water is a breeding ground for mosquitoes and mosquitoes bring heartworm, so I wouldn't let him drink that water. You could always bring fresh water from home with those little pouches sold at PetSmart. I'm sure this once won't do any harm but I would be careful in the future, You also never know if an infected dog drank from it or even peed in it...parvo, distemper, etc.