Water filters don't filter out minerals. Just to clarify.
I have hard well water. It's delicious. Since my cats are canned fed none of them drink water at all now so I don't have to worry about it anymore. My FLUTD girl was the only one who drank, while she was on the c/d kibble, though she was a poor drinker always. I'm beginning to wonder if the water was her problem all along.
I do add water to one cat's food, to slow her down and help her feel full. Her pH reads steadily at 6.75. I'm going to try cutting down the water in her food and see if it makes any difference.
Our cats don't drink much water either...if any.
I also add water to their food.
Hubby adds a LOT more water to their food, than I do. He turns their food into soup. I recently noticed that when he feeds the felines, one of them always barfs about 4 hours later.
Not sure if it is a coincidence or not, so the last two days...I've been doing all the feeding.
No massive amounts of water added to food...no barfing.
I'm leaning more towards the amount of water being the issue.
I'm going to continue this "test" for a few days.