The property is 50 years old in a semi-rural area. The tank started overflowing 3 years ago. I installed a dry well for water softener/iron filter/laundry grey water and had the tank pumped. When I had the tank pumped water flowed back into it from the outlet. I don't want to replace the field, as it is at a depth of 4.5 feet. There is no distribution box, but I was able to find the outlet pipe 20 feet behind the septic tank at that depth. There are also some maples growing near or possibly in the field. I removed one of them, but don't know if the other 2 have caused blockage. What is the best way of evaluating the field to see if H2O2 will clean it up, or if it needs to be dug up and replaced?