Looks like reflective tape around his saddle bag.
I ask about the water purifier because it's been important for me to have one on some of the rides I've done. I don't know where Richard Glover rides, but, in NC, his bike might take him to places where it's good to have one. I can never bring enough to drink when I take my bike into the mountains for long rides, so I bring a purifier and pull the sweet water of life out of streams and rivers. Anyone on a touring rig with four bottle cages, is someone who might benefit from being able to fill those bottles in the middle of nowhere on a long ride.