no, the inspector would not know. i would suggest you call and arrange a a meeting between you, the inspector, and your contractor. tell the inspector the contractor and you disagree on whether this matters or not. regardless of how this goes, it is going to cost YOU money. either you have to tear down the deck and be out what you owed the contractor for it, or you have ot pull up and move the tank and be out this cost. like i said earlier, if the contractor hit the tank when digging the posts he knew it was there, and that is your ONLY hope of laying blame off on him. if you tank is deeper than the posts go and he did not hit it, then he had a reasonable expectation of the tank not being there just like you and the inspector. in my area the tank HAS to go where the drawing shows. the health dept tells you where on your land you can put it and then you build your house around that. i have seen people who had a choice of build the house sideways or build a different house because the health dept told them there was only 1 place they could put the tank.

Too little information. Steel tank or concrete? How old is the system? What makes you think that the previous pumping service ripped you off?

no, it wont hurt a thing. as far as building fumes, depending on your tank you may have a layer of HIGHLY explosive methane gas there at all times anyway. this is by design and nothing to worry about.

Hi @Simplysherona, sorry if I sound patronizing, but I am afraid for you and want to ensure you get the very best advice you can before you purchase this property. Posting on Houzz is great to give you direction, but if you go into this transaction without knowing your options and risks from a local expert, you may pay for this for a long time. A holding tank may be perfectly adequate and the cost to pump it out regularly may be very reasonable, but until you have real information from people in your area, it's only a guess. You indicated there was a previous septic system. Do you have it in writing that the previous tank was removed and remediation was done properly? Have you talked to the neighbors and found out their experiences with the holding tank setup? So many questions need to be answered. I have totally been star struck with houses e.g. our first house, a 1880's shotgun, did not have a sink in the bathroom. I didn't notice that until after the purchase. Duh. In our 1940's second house, the washing machine drained into the back of the three acre property. That was all fine until Chicago winter set in, the drains froze and I had to manually start and stop the washer to haul water out until it drained. Who knew to ask these things before we bought? Certainly not us as we were young fixer uppers, struck by the possibilities of the house, not the as is. $$$$ duh. No one on Houzz can answer the questions you asked in your last post unless they inspect the property. Get real advice from local experts. You can never do too much due diligence. I want you to have a lovely lake house, not a nightmare.