For water, 1 mole = 18 g= 22.4 liter. But practically, how 22.4 liter is equal to 18 g?
For water, 1 gram is approximately 1 mL.
22.4 L/mol is the molar volume of an ideal gas at STP.
Since water is not a gas at STP, you can't apply that.
If you had one mole substance that is a gas at STP (hydrogen, nitrogen, carbon dioxide, etc.) you could say that they occupy a volume of approximately 22.4 L.