Poured a bit in a glass mid stream as I was emptying a gerry can and it looked like good water so I tasted it. Couldn't taste or smell any diesel.

Interesting, when I was poking around the bottom with the small hose I picked up a lot of junk sitting on the bottom. It felt like the tank has a kind of sump pocket at the bottom and as I liposuctioned the hose around the bottom it did a nice job of cleaning the bottom of the tank.