YES, you are totally right about your constipation.
The epithelia of our intestinal is regeneration fast. Every 20 days it will be replaced. Old cells will fall into the lumen and build up the constipation. (The microvilli will only last 1-4 days)
So, the question is: What is the daily amount of this dead cells? Up to 250g = 8,8oz
Over 40 days you could build up 10 kg= 22 Pounds.
The regeneration of the epithelia might slow down a little bit, because of the fast, but not to much.
If you don’t want to dehydrate, you need to drink the right kind of water.
Spring water with a very high amount of minerals. Sodium (Natrium) is very important, for hydration and blood pressure. We lose a lot be sweating.