Septic systems are usually inspected when you buy a property. Usually the septic company comes out and cleans out the waste in the tank, then they inspect the tank for any leaks. And they will advise you on upkeep...and paint.
Talk to your realtor, they should have recommend this in the first place.
Good luck on the inspection, replacement around Mass is usually pretty expensive...12- 20 thou. due to too many regs.