Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern for Addy.
There actually is quite a long list of possible reasons why a dog might consume more water:
Diabetes Mellitus (high blood sugar)
Urinary tract infection
Psychogenic (which is basically ruling out other causes)
Increased sodium in the diet
Infection in the kidneys (pyelonephritis)
....and this is just a partial list.
In most cases, unfortunately, blood work and a urinalysis will be needed as a starting place to try and determine the underlying cause of a dog's increased thirst. Then based on the results, additional testing might be suggested to get to the bottom of the problem.
In some patients, it can be a challenge to determine the underlying cause. I've also seen some patients who drank more water for a short period of time but then returned to drinking a more normal amount. This isn't common but it can happen.
I hope this helps. Deb