We ran the SaaleHorizontale as a long training run for our (hopefully) upcoming races in summer. We started early morning in the center of Jena and followed the provided GPX-Track around the city until we reached the university-hospital south of the city, where we parked our car.
We carried all water and food with us all day and did not resupply, which resulted in a quite heavy pack. There are some small streams and one public fountain on the way, which you could use to refill water (I'd recommend using a filter though, just to be sure). If we did it again we would probably carry a bit less water and refill on the way, but it's definitely possible to run all of it without refilling (at least in cold temperatures).