Clogging of the drain pipes. Backflow of the waste from the drain field to the septic tank. Standing water or wet, mushy grass over the leach field. No discharge of the wastewater from the septic tank to the leach field. Slow draining of the wastewater. An unpleasant odor comes out from the leach field, drain pipes, or septic tank. There is water or wet grass in the leach field. Toilet flushing problems such as no flushing, slow flush, or low flushing pressure.