LOL, I just answered your other post...

If they got enough water into the charcoal canister, I can see how that would set off this code. But on my Accord, the EVAP canister is underneath, near the gas tank, not in the engine compartment. It has a filter on the vent, so I don't think you could get into trouble with a water hose. Civic has to be somewhat different, so you'll have to check a shop manual for your car.