I have an old house and the cast line is 4 inch I believe. according to the sewar guys there camera says we have roots. When I snake the roots are so far that I thihnk it is in there line. At any rate we get back up into basement every year. I am sick of this it seems to happen just before my planned de rooting. No matter when I plan it. I am thinking of diggin up the line and replacing the connection so roots cant get in. If I do this I have 2 issues. First should or could I use a backflow preventer? Not sure this is a trouble free solution. It could get stuck open. or other. So is there a something to keep it from entering the house in the event of a swewar clog? The other is what to do with the dirt while from the huge hole. It would ruin the yard. I guess that would be the price we have to pay, and it may not be that bad. Getting that big of a hole dug is a project, it will need shoring. There will be wires in the way so much of it will need to be hand dug. Anything you can help or add would be great.