Cleaning a field drain

Does anyone know the best way to clean tree roots from a drain field tile? I have had it cleaned out with a snake and rotating blade to cut them but the line only goes 100ft. Their is only one riser and it is at my house. The drain line extends about 1000 ft. over 6 houses. It is blocked with tree roots. Will chemicals work? thanks.

If tree roots have grown into it all along its length the best thing you could do would be to dig it up and replace it; and share the cost among the 6 home owners. You could try copper sulfate but, I am not sure how well it would work in your situation. Is the line empty other than the root? Or, is it half-full of dirt? What size line are we talking about?