You should never give your pet water that is not fit for human consumption. The problem is that even for water that has been certified for human use, the answer to this question becomes even more complicated due to the additives that may be present in the water, such as fluoride. Thus, the answer to this question depends a lot on where you live.Cats don’t like water with high levels of additives such as ammonia and chlorine and this is the main reason why cats like to drink running tap water. Unlike the water that you put in the bowl, flowing water is better oxygenated and the chlorine evaporates off.If you live in an area where the tap water is heavily chlorinated, there is an easy solution to make the water tastier for your cat. You should leave it to stand in the bowl for around an hour before serving it to your cat. This should allow the chlorine to evaporate and the water will become much more appealing.As far as fluoride is concerned, the danger is very low since in order for your cat to get a deadly dose of fluoride it will need to drink an absurd amount of water. If you want to be certain that there are no other contaminants in the tap water, you can contact your local water utility company or check its website for more information.