I use the VAUDE Aqua Panniers.

https://www.amazon.com/VAUDE-Backuminum-Single-Backpack-Black/dp/B076KRBYG3/ref=sr_1_3?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&keywords=vaude+aqua+back&qid=1557749393&s=gateway&sr=8-3

Great Company and products. PFC free and climate neutral manufacturing process.