I’ve noticed the appearance over the past couple of years of communal water bowls outside shops and in public places frequented by dog walkers. I always appreciate this small act of kindness by whoever takes the time to lay on fresh water for the local dog population and my two regularly use them. Recently, however, I was cautioned by another dog owner that they spread disease and she would never let her dog use one… So to the font of all the knowledge. THE INTERNET.
Because my two Lurchers from time to time find and eaten disgusting rotten stinking decaying rancid unidentifiable “stuff” I supposed that they had a pretty robust system of dealing with bacteria taken orally and it turns out that there are actually very few communicable diseases that are spread directly by mouth.
Contagious diseases in dogs are much more commonly spread in other ways and the dangerous intestinal pathogens such as parvovirus and roundworms are spread through fecal-to-oral transmission. So these particular organisms can’t be spread from drinking from a communal water bowl unless there is fecal contamination in the bowl.
However there are other infectious diseases that are spread through the respiratory tract such as the pathogens that cause kennel cough and canine influenza which are expelled during coughing or sneezing. So theoretically if an infected dog coughs or sneezes around the bowl, there is the potential for other dogs to be exposed to these respiratory pathogens.
Finally the the canine papilloma virus (which causes a minor, self-limiting syndrome in dogs) can spread through saliva.
So basically if your dog has a healthy immune system its pretty unlikely that they will contract a serious disease from a shared water bowl.