The question of small water users having no centralized wastewater collecting, cleaning and discharging system is of maximal actuality in Romania. Therefor economically efficient solutions are looked for. For disperse mountain villages, farms, or detached households traditional systems, with high maintenance expences because of long networks for small flows, can be economicaly not advantageos. Very small capacity treatement plants are a solution for such cases. The aim of the experimental part of the present work is to simulate situations, damages which can occur during running of a low capacity wastewater treatement plant. Low capacity hosehold wastewater treatement plants are economic alternatives which remove the disadvantages of emptyable basins namely the high costs, the frequvent empying operations, with unpleasant smelling, continous danger of groundwater infection, need for massive and expensive concrete buildings. The proposed plants are based on a classical treatement technology and need emptying of the exess mud only once or twice a year. In opposition with the case of classical plants, the mixture extracted from the proposed low cost systems does not smell and has a relatively low content of solid matter
