1QwkSport2, when you leave fuel in you tank all the time, does your silicone clunk line tend to get soft and mushy on you? Mine sure does inside of the fuel jug. For the original question about water getting in your fuel. You said the DuBro jug system might not be sealing well enough. Usually they have an o-ring on the probe that has to be in good shape. When you store your jug and it gets cold at night or the next week, do the sides of the jug tend to suck in a bit? If so it is sealing very well. I use the Sullivan (or is it Slimline?) cap and probe system with a tiny o-ring and it seals remarkably well. An extra o-ring came with it but after about 5 years it is still sealing well. If there is a small amount of fuel in the jug it works great the following summer.