But if the venturi blocks due to icing, the engine stops and later the carb is inspected, the ice will have melted and left water in the carb
Crab this ain't a rocket engine.
As Eric says ice forms in the venturi, outside the carburettor. If our good engineer (who is probably enjoying this charade) drains water out of the carburettor he drains it out of the carby bowl, where it has got in via the fuel line from the dirty fuel in the fuel tank.
Carby ice forms from atmospheric air when it goes past the carby via the venturi (which adjoins the carby as part of the same structure) en route to the engine and never gets into the carby.
To stop air getting into the carby there is a fuel deck pressure which is the weight of fuel in the carby as it is let in via a float valve from the tank due to gravity on a normally aspirated system. On a turbocharged system the fuel deck presure in the carby is balanced with the fuel pressure pumps against or more than the inducted turbocharged airflow pressure, so that the inducted air - and fuel - cannot go the wrong way.
A pressure differential is provided by a lower pressure in the venturi to suck fuel from the positive pressure in the carby bowl to the engine via the mixing ports in the venturi.
Water in the carby is dirty fuel.
Carby ice is an atmospheric condition causing ice in the venturi which impedes the normal fuel/air flow to the engine.
Another can and perhaps a rum chaser for the ginger beer please.
cheers tet