Water staining area around outside wall Nautilus control panel inside access to pump

I have noticed water staining in area around outside wall on and around Nautilus control panel inside access to pump and Alde system  Has anybody had this problem and where was the water coming from.  No evidence of water leaking from fittings inside camper.  Could be water from hose connection and use of black water flush?  Connection tested water stained areas with moisture meter very wet.