There we are then, interstital condensation causing water to get into the container, bacterial growth in the water and transfered into the UAT, if you are going to store fuel over any length of time ensure the container is absolutly full this will leave the minimum amount of surface area for condensation to form on, hence less water into the fuel and less area for the bacteria to grow on.

I would recommend the use of a ''Mr Funnel'' filter to get rid of the water and growth when transfering the fuel from your storage container into your fuel bowser, and don't leave fuel in the tank or UAT for a prolonged periods.

Mike