Reminds me of the old Neil Williams story. Flying back from somewhere east of the iron curtain at all of his fuel stops the bowser was a horse and cart with 45 gallon drums on the back. All of the "bowser drivers" produced a fuel sample before filling him up. On his first refuelling stop in West Germany he was met by an ultra modern state of the art fuel bowser and was filled up. About 10 minutes after getting airborne he suffered a partial engine failure due to... water in the fuel.