I finally had a chance to run this entire route! I got lucky with a chilly November day, so I was able to complete the route unsupported by getting water only from the public drinking fountains on the route. I started from Balcones District Park at 6:40 am, running counterclockwise with two handheld bottles, 16 oz each. I filled them both at Bull Creek Park (mile 9) and then made it to Barton Springs (mile 25) where I filled them again. In the next section I drank as much as comfortable and filled them again at Guerrero Park (mile 31). At Govalle Park (mile 33) I topped them off and filled a bladder with an additional 20 oz or so. It was a bit warmer now and this was just barely enough water to get me through some slower miles and to Walnut Creek Park (mile 47), where I filled one bottle to finish off the run.
10h 43m 8s