I agree on getting some blood work and maybe a urinalysis done, ESP on the older ones.
I agree w/ LoveMyBostons....Any dog with new excessive water consumption & urination, needs to see his Vet for A complete blood panel.....MY first thought is Diabetes because he's losing his eyesight, too....These diseases are much easier to treat if caught early and can provide your guy with much relief with the proper medications....Good luck & let us know what you find out.......Karla
You might want to get some bloodwork done by your vet. It's possible he has the beginnings of kidney disease/dysfunction.