100LL has always been squeaky clean for both water and particulates.

The only time I've ever seen contamination is in avgas. Mogas, with
our filtration system especially, is never an issue.

I always figure it's because of the tiny amounts of 100 LL some of the
out-of-the-way airports we visit actually sells. Some of that gas in,
oh, let's say Maquoketa, Iowa, is probably two years old, and God knows
what the inside of the tanks look like.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"