An automated wastewater treatment miniplant intended for installation and use with individual residences. Wastewater such as raw sewage is received in a settling tank to remove suspended solids, and then flows to an intermediate tank where the sewage is aerated and churned to promote aerobic treatment of organic materials in the sewage. When the wastewater in the intermediate tank reaches a predetermined level, a batch of that wastewater is transferred to an aerator-clarifier tank where further aerobic treatment of the batch wastewater occurs under controlled conditions, without dilution with incoming wastewater. Further aerobic decomposition of the wastewater takes place in the aerator-clarifier tank. Sludge is allowed to settle in that tank, and supernatant liquid within that tank is periodically withdrawn for dispersal in a drain field. Sludge is periodically returned to the intermediate tank to augment the biomass in that tank. Some sludge is periodically wasted from the system. The wastewater treatment miniplant optionally includes a separate tank for receiving and disinfecting supernatant liquid withdrawn from the aerator-clarifier tank. That disinfected liquid is dispersed in an underground irrigation field or in a drain field. The miniplant is automated under microprocessor control, and can report faults to a central location and exchange other information with the central location.