Wells, Sump Pumps and Septic Sewage Systems - Septic system filters

Do the filters advertised on the net, specifically the washer lint filters, do any good? My septic system is marginal, by any means. Do these filters really help? My wife washes a lot of clothes each week, and the waste all goes into the septic system. Can't redirect the washer effluent, although I would love to. Also, I have several trees that have grown up in the field line area (on the hill above us; pump system). The trees are mostly pines, do they have a thirst for sewage water? Should they be cut? Basically, should the field line area be cleared of everthing but shrubs and grass? Thanks for any help.

Although pines have surface roots and don't cause the same problems as a tree like a maple I would cut them. Why take a chance. You want as much sun as possible to help dry out your field area.