Maybe you never found water in the filter, I'll bet you a box of sugar free cookies that you have had plugged nozzle strainers and clogged pump strainers.
They all go away with the installation of a Spin-On at the tank. And any water will end up in there. And just because you don't see water in the bottom of the filter, doesn't mean it wasn't absorbed by the oil in the form of sludge.
If you're going to be dealing with Bio-Fuels, you better count on water.