bad inspection/ issue with septic system

[Tomi Stoya]

I have an accepted offer for the purchase of a duplex. The septic tank inspection however did not come to be very good. Inspection of the drainfield indicated 10" of ponding effluent. Also, there is no effluent filter in place. Based on the amount of ponding and the age of the system, the inspector recommends replacement of the absorption system.

How big of an issue is this and could it trigger the private sanitary system inspection contingency? Having effluent (waste water) in your backyard would be a health hazard, wouldn't it? Per accepted offer the sanitary system "is not disapproved for current use (is hydraulically functional and structurally sound)". Per inspector complete replacement of sanitary system will be between $6K and $12K.

I am still new to real estate, so I very much appreciate the opinion and feedback of someone who is more experienced?