At 25 ppm, PEOPLE can still swim safely, but you might ruin your swimsuit if you are in it for a long time. It won't hurt your skin, unless you are sensitive to chlorine. I would think it would be the same for dogs. As far as drinking it, as far as people or children go, small amounts won't hurt you, but if a dog is drinking large quantities, I am not sure what that would do. It's a good question and I hope someone more knowledgeable chimes in.