biochemistry - Raphide toxicity in Pothos plant

Recently I found out that the common houseplant Pothos (Epipremnum aureum) is toxic to cats and dogs due to the presence of "insoluble raphides." I have a lot of these plants around my house and my cat drinks water from the vase that they are in (I put drinking water into the vase that he always drinks from). He doesn't chew the Pothos leaves, he only drinks the water, is it still dangerous? I tried several times to give him water in an ordinary bowl, but he prefers the water that's associated with the Pothos plant, so I thought that maybe the roots of the plant excrete something nutritious (but I guess that's not the case, apparently...).
Is it harmful for an animal (cat) to drink water that has a Pothos plant immersed in it?
Also, my other cat does chew on the Pothos leaves (he goes crazy for them). Is it possible to have immunity and not be affected by the toxic chemicals? I read that chewing is supposed to provoke stomach irritation, but I would think that if the cat that chews the leaves suffered from irritation he wouldn't keep getting excited about chewing the leaves...
So what is going on? Many thanks!