I am working on an appraisal for a tenant who wishes to make an offer to purchase the subject property from a family member. The property is in a "rural residential" zoning, 1 acre minimum lots that have wells and sewers. I am dealing with some of the complexities (like - where are the COMPS??), but have one specific problem/question: The knowledgeable tenant and I had a conversation about the septic system's size ("small") and age (50 years). I instigated the conversation when I found that the home has a garbage disposal, a no-no for septics in my world. The tenants (2 adults, three small children) have been in the home for 8 years and mentioned that they have had the tank pumped once since they have been there. This is a 3 bedroom, one bath house. New septic tanks in the area are required to be installed above ground due to the high water table. The tenant is aware that they would have to deal with the size/age of the tank before they could enlarge the house (1450 sq ft +/-, 3 bedroom, 1 bath). This might or might not require an above-ground tank. No items of physical deterioration or functional obsolescence will be cured prior to the offer being made on the house - the appraisal will be "as is". Given that the septic is not of a size or condition (per the tenant/client) to "cure" the functional obsolescence of the floor plan, what statement would you make in the appraisal about the septic? I will include a statement about pumping and inspection by a qualified expert, but how should the general inadequacy be noted? Is it both physical depreciation (amount currently unknown) and functional obsolescence? Thanks for your assistance!