Yes it is . I put a Tbsp of Apple Cider Vinegar in their drinking water. I buy it at Nutrition House which is a natural health store, here in Canada, I don't know if you have it where you live, but you can find it at any health food store or GNC store. I buy the Bragg organic one, it's $9.99 for a 32 oz bottle. You have to keep it in the fridge once it's opened. I also use it myself in a bottled water once a day, and you can use it on your salad. It has so many health benefits for yourself too. It's all natural so can't hurt, I don't think giving more would anything, it might just be too bitter, and then they wouldn't drink it. My two don't mind drinking the water, they drink it like normal.