I moved a while back, but I have not registered this with the municipal authorities. Should I send a notice of objection?

Are you relocating within the same water control board area? Then you do not need to take any action. Please notify the municipal authorities of the change.
Are you relocating outside the same water control board area? Then please send an objection notice via My RBG. Send documents proving from which date you no longer make use of the home. For example a copy of the termination of your home rental agreement. Have you sold your house? Then send a copy of the key hand-over. Please notify the municipal authorities of the change.