That is very sad I didn't think it was that dangerous...my dogs swim/drink out of the pool all the time.

But I found this at healthypet.com

QUESTION:

My dog likes to sneak drinks out of our swimming pool. Will this hurt him?

ANSWER:

The occasional drink of swimming pool water won't hurt most dogs. The concentration of chlorine and other chemicals in the water is low enough that your dogs would have to drink quite a lot for it to be dangerous. People sometimes swallow pool water on accident too, with no serious consequences, so there's no need to worry.

But I guess it could depend on the size of the dog and the concentration too, we have a huge pool and we don't usually keep up with the chlorine like we should...I guess thats a good thing. Thanks for sharing.