My cats drink from our swimming pool

You need to take your kittens to the vet. Dehydration is very dangerous to kittens and it might be fatal very quickly, if not treated in time.

The best thing is to avoid chlorine in a swimming pool where animals are likely to drink water. There are better and less harmful chemicals you can use, like hydrogen peroxide.

And there is the obvious solution of keeping the cats away from the pool.

Other animals will drink from your swimming pool too, so from an environmental point of view it is best to avoid chlorine in your swimming pool.

Your water supplier does probably add some chlorine to the water, so you can most likely reduce the amount of chlorine you add to the swimming pool.

There are several ways to disinfect your swimming pool, your options are: ultraviolet sterilizer, which uses light to kill bacteria and viruses; and ozone generator, which uses ozone to disinfect and remove color and odors from the water. Both of them are harmless to animals and people if used as recommended.

Hydrogen peroxide is an agressive oxidizer that removes color, odors and disinfects the water. It gets neutralized in a few hours (it gets broken down to clean water and oxygen).