Atwood does not have an anode rod, Suburban does. If the plug hex flats are 1 3/8" it is a Suburban with an anode rod inside the pipe plug. The Atwood plug is 5/8" flats if I remember correctly. In either case it drains outward, and the galvanized panel is sealed to the trailer wall to prevent getting water into the RV. If you remove the electric heating element, yes water will drain into the RV.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"