The average cost for an inspection is between $400 and $700. Some towns require septic pumping at the time of inspection. Pumping a septic tank usually costs $180 to $250, depending on how many gallons the tank holds.n Massachusetts you can get up to a 40% tax credit towards the cost of repair or replacement of your septic system provided the cost is $15,000 or less. The Commonwealth provides a state tax credit of up to $6,000 spread out over 4 years to defray the cost of septic repairs to a primary residence.