I also want to add the lady at the nursery said the birch would be fine because it's so skinny but she also said I could do poplars which I heard/read are TERRIBLE near septic systems so I wanted other opinions.

Just for reference, we have three quarter acre lot with am 8 year old, three bedroom, three bathroom, etc. house. Our septic system consist of a 1000gal digestion tank, and a 1000 gal, water holding tank. There is a line of about 80' to the distribution box which supplies 3 - 130' leach lines.

The three leach line cover an area of about 4500 sqft. The length of the distribution line, plus the area of the two tank must also be consider when planting. The system snakes over 200 feet across our back yard.

Also there is an area that is designate a rebuild area equal to the area of the leach bed. If you plant in this area, any thing there will be taken out when the digging is done to install the new replacement leach lines.

Our system is a what is called a pressurized system. In our previous houses, as I remember, the non pressurize system's leach lines covered only a slightly less area,

There are many different configuration for septic systems. When they are installed the topography of the lot, the type of soil, technology, and City, Local, State, and Federal regulation must be considered. Some systems take up more space that others. To my knowledge there is no ONE modern system.

Before starting to planting you need to know what kind of septic system you have. With my house (8 years old in NC) the system is described in the County Health Department inspections which is part of the building permit. In NC this was provided to us as part of the closing paperwork when we bought the house. The septic system is one of the inspection that has to be performed during the closing.

As for planting trees, If you don't plant a tree in the middle of the leach field or on top of the tanks you should be OK. We have a wooded lot. When the septic system was put in the problem areas were clear during the installation of the system. Since we moved in I have respected those area when considering what I plant.

The serviceberry and maybe some redbuds are what I would limit myself to.

I can "see" the indentations of my field lines. If you can't I'd be interesting in finding out where they are. Someday you're going to want to drive in the yard or something.

I'd stay away from willows, maples, poplars - but otherwise most other trees/shrubs should be fine. There are university publications addressing it...Google 'planting on septic leach field'...

Have friends in IL who own/operate a private arboretum. Septic leach field lines run out through a heavily-wooded area. Once or twice yearly flushing of some copper sulfate down the toilet keeps root incursion at bay; 30+ years with no issues. CuSO4 to control root incursion

Before you plant, study the plan of your septic system. As mentioned above, it should be part of your closing documents or on file with your local building authority. It will be signed off by the designer and that is who you need to consult about potential plantings.

There are many different styles of septic systems and some are more tolerant of close plantings than others. I was just called to recommend plantings for a new field for a house in dense woods with many existing very large trees in very close proximity. The septic system was designed around their root systems. Obviously, trees and septics can coexist.........it's a matter of choosing the correct ones.

Your neighbor may be more receptive to the idea of you planting evergreens near/on their property line if you suggest that they can use them as a backdrop to variously beautiful shrubs and flowers.

It's worth a shot. My neighbor planted 3 on the property line and I love it as a privacy hedge and as a backdrop to hydrangeas and perennials.

We built our house ourselves with my father in law who is a carpenter, I know exactly where the tank, line and runs are and can still see the indents on the lawn. Our tank is south of our house and the main line runs right west to the back of our yard and the runs come out from it like a letter P if you get what I'm saying, so basically I want to plant right along the main line, not the tips of the runs. He should know the type of tank and I wonder if he knows anything about planting trees, I never thought to even ask him but he knows we want to plant trees and never said that's not a good idea. I must say I really regret that I didn't convince him to move the field a little more to the north to make room for trees, but growing up in the city I had no experience with septic tanks/fields and had no idea you couldn't plant trees around them. Our field is huge it literally takes up the whole back yard but it's what they said we needed after we sent in our soil samples. We also have huge old willows at the end of our field that were there when we built. I would have a forest around my house if I could! One nursery said minimum of 25' away from septic run for the larger conifers I was asking about, I didn't consider the skinnier trees until another nursery suggested them.

BW,

Most nurserymen are not civil engineers or soil scientists... I know there are some good knowledgeable ones around, but all of them I know in this vicinity are just tree salesmen; they probably aren't competent to be making recommendations or cautions on what or where to plant, with regard to proximity to a septic leach field.

And, as akmaine said, just because it's a narrow, columnar cultivar, it's roots will NOT be a mirror image - of what you're seeing above ground.