there is something else that I haven't figured out exactly what it is that causes him to be itchy, and he starts scratching a lot and biting on and pulling out his fur and has watery eyes.
OMG I noticed that my cat has that too sometimes. Maybe it's the food that makes him so? but it could be chicken stuff because when we give him fish he's not doing that bad. My cat drinks a lot as well and thankfully, he does it himself and I am not too worried on that front. Also same here, it's not dry over here but hot enough that one time, he got a heatstroke, which wasn't fun to deal with. Thanks for this comment and all these possible reason that potentially causing his fur to be that way.
The vet told me that chicken and fish are very common allergies for cats, and of course that's what most cat foods are made of! At first we thought Yuan might be allergic to both, but thankfully it turns out he can eat chicken, it's just fish that makes him sick. So it could be that maybe your kitty is the other way around!