Wouldn't shutting off the fuel valve after every use stop the leaking?
If the float leaks when the engine is shut off then it will also leak when the engine is running.
If it is leaking when running then you may be running rich due to the fuel level being too high in the float bowl so JSALIS is quite right about it needing to be fixed.
Turning the fuel off when not in use should technically not be necessary .
However I fit taps & instruct owners to shut the fuel off as a belts & braces approach cause it is easier to turn off a tap than clean leaked fuel out of an engine, replace head gaskets or even bent cranks.
At least weekly some one posts to the forum that their engine is blowing smoke or is cranking hard.
They get asked to check the oil then come back with it is too high or tell us they changed the oil and there was too much in there