I started off this Water Fast by doing 2 days of dry fasting, hoping it'd kick start me into ketosis quicker. I drank water on day 3 and then started a 24 hour dry fast to day 4. At that point, I felt terrible, so I had to drink.
I hear you on the Day 4 and 5 being the breaking point as before this fast, I could only get to 5 1/2 days as my endpoint before the pure pain compelled me to eat.
Good luck on the fast. Maybe you'll make it farther than I did.