I touch on sediment in the urine towards the end. Super important!
In my experience with dry fasting it has opened my eyes to how little water we actually need. I went from drinking a gallon of water a day thinking it would clear my body better to realizing the kidneys react better with less water. It has lead me on the path to truly understanding drinking to thirst, I used to drink because my tongue felt dry on a Water Fast but realized it was the white coating that made it feel dry. There is a difference that I finally realized between thirst and dry mouth and dry tongue.
I currently dry fast in the first 2-3 days of my fast then switch to as minimal as possible while making sure I get enough. I definitely don't exercise while doing this.
On another note, try urinating in a clear glass jar and setting it away for a day and see if there is sediment in the bottom of the jar. If you have sediment your kidneys are removing bad things, if not your cellular waste is staying in your body and not being eliminated.