Oh no. I hope your usual gas station is a name brand, like Mobil, Sunoco, Shell, Gulf, etc. Even if the owner is an independent franchise they have to meet corporate standards to maintain their franchise. So if you get no satisfaction from the gas station owner who you don't seem to trust go right to corporate.
You may also wish to contact your state's environmental authorities as it sounds like his underground gas tanks have a leak and water is getting in from the thunderstorms. If water can get in, gas can get out! Which means groundwater and soil contamination. Also how many other people who stopped for gas at this station the same morning you did got water instead of gas and ruined their engines!? The owner of the gas station is going to have a lot more problems on his hands then your claim. I am sure there will be many claims, plus he lost a whole shipment of gas as anything in the tanks was ruined AND he may have a whole environmental clean up on his hands. Hope he had good insurance and it was paid in full. A catastrophe like this could easily put him out of business. Get your claim in FAST!