A leach field of a sewage system is dewatered, to restore its function when it is at or near failure. In various embodiments, water is withdrawn from the points in the leach field, preferably from the conduits, by means of suction or sub-atmospheric pressure. As water is drawn from the soil, air from the atmosphere or from an air mover enters resultant spaces in the soil, to restore the influence zone and better treat waste water. Forced air flow is used to fissure the soil, to aid dewatering, and separately, to restore the leach field.