In any real estate transaction everything with respect to diclosed repairs is negotiable between the seller and the buyer. As in the case of the REO property that you seem to be the buyer for, the cleaning and inspection costs for the septic tank and system is no one's responsibility unless negotiated for.You as the buyer have the duty to do your own due diligence regarding property inspections of all aspects of the property before close. If you want the bank owner to take care the issues regarding the septic tank, then you need to negotiate such before close of escrow in writing.