Bladder Treatment causing hard stools.

I have overactive bladder issue. Urologist prescribed Roliten 2mg twice a day. I am taking Terol LA 2 instead which is its replacement; it's the same compound. Urologist also prescribed minimal overall water intake of 1.5-1.7L per day. This second prescription is causing several problems 1. My stools come out hard and it seems to be inflammatory for my piles and fissures. I saw blood in my stools the other day, but it was only once. It didn't happen more than once. 2. The prescribed tablet (Roliten/Terol) causes dry mouth as a side effect so maintaining the low water intake is difficult. The treatment protocol is contradictory to itself. 3. Finally, I am also taking Rejunex CD3 as a supplement for Vitamin b12 and d3. Due to low water intake, it makes my pee smell really bad What is the solution here? If I increase water intake, will it reduce the effect of Roliten/Terol tablet compound?