well its a hydrocarbon and has a very low boiling point and vapor pressure meaning it diffuses into the atmosphere very well. this is similar to alcohols which do this better but the smell sticks around because it is so light weight and volitle. one of the major dangers of it being in your water is that it will sit on top of the water creating a barrier for gas exchange etc. as for the contamination of your water it is most likely very minimal however again knowing how much we invest in the hobby i would dump it just to be on the safe side. but you need to remember what paracelsus said " the devil is in the dose". there may be enough gas in there to be toxic or just enough diffused into the water to provide a toxic level. everything is toxic it just depends on how much you get and the amount of time. the reason why it gets into everything also is because it wants to put as much space between itself and the other gasoline molecules.... i can ask my polymer professer for more if you need more info