Yep. I'm deficient in the antidiuretic hormone, arginine vasopressin. So, unmedicated, everything I drink I will pee out very quickly. I spent a year undiagnosed, drinking between 8-10 litres a day and was still bordering on being dehydrated. I can't express in words how awful it was. With that in mind, my input is considered mild compared to some, who drink up to 20 litres a day. Imagine that.
Now I'm medicated I have to watch what I drink, within reason, and ensure that meds have worn off, and thirst starts again before taking the next dose. That way I release any free water and save myself from low sodium and a hospital visit.
It sucks, but it won't kill me.