A leach field is a series of rock-filled trenches where filtered water leaving a septic tank is allowed to percolate, or "leach," down into the ground. According to the El Dorado County Environmental Management Division, more than 50 million people in the United States rely on septic tanks and leach fields for waste water management. Leach field failure is a serious problem, contaminating ground water and potentially causing a public health hazard. Recognizing the signs of leach field failure enables quick action to avoid ground water contamination.
Check drains on showers, bathtubs and sinks for signs of being clogged. If multiple drains are clogged, seemingly without reason, the effluent waste water may have backed up into plumbing, indicating a saturated leach field.
Observe the grass the sits on top of your leach field. Healthy grass is ok, but grass that is brighter green in contrast to the rest of the yard indicates that waste water is not filtering downward through the soil.
Watch for puddled water or marshy, saturated soil above the leach fields. Heavy rains or an overloaded septic system can oversaturate the leach field, preventing the waste water from filtering downward.