One area that has not been covered is the accumilation of soap Soap is the #1 reason to have a septic tank pumped. I would think that after a few years you will start having problems. BUT then again with heavy rains it just might wash it deep enough not to bother your generation Another is chlorine. From a personal experimation to control damp-off with chlorine, I found that 2 drops of chlorine in 8 oz of water, as a soak, would kill plants. I did find that 1 drop per 1/2 gal, misted on the surface, when the top of the soil was dry did kill damp-off without hurting plants. These amounts are a lot less than in a load of wash. Byron