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at the bottom was water(fuel is hydroscopic{absorbs water}) fuel from airfields thats kept in underground tanks absorbs moisture
You make it sound as though water is endemic to avgas. Like many other things it depends on the quality of the handling/storage. The fuel delivery system at my local neighboorhood airport has a mass of filters and water separators.
The transfer of fuel from cans, external fuel tanks, or other non-aviation transfer systems introduces the possibility of water mixed into the fuel. Race gas stored in drums can accumulate water just as easily.
Carb icing is addressed by controlling the Reid Vapor Pressure of the fuel, not by additives. Toluene (it burns) is one additive, it's used to lower the freeze point and other additives in small amounts help prevent gum formation in the system.
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