Technical design of sewage treatment plants with a built-in sand filter enables to acquire 98% of treatment efficiency which means in practice quite pure, odor-free outgoing water having characteristics of service water suitable for further use. Monoblok-T is a biological sewage treatment plant with intermittent operation of Sequencing Batch Reactor (SBR) which consists of equalization tank, SBR and sediment trap. This plant is designed for municipal waste water for capacity from 100 to 500 equivalent inhabitans. The entire operation of the plant is controlled by a microcomputer allowing to adjust the cleaning mode according to the volume of waste water. The plant control system can be connected to the central computer what enables to control large number of plants from a single centre. FLEXIBLOK is a biological sewage treatment plant consisting of two activation tanks with intermittent function Sequencing Batch Reactor (SBR), which is completed by a course pre-treatment and sludge handling system. This plant is usually designed for capacity of 500 to 5000 equivalent inhabitans, however the upper value is unlimited. The operation of entire plant is controlled by a central computer, which optimizes its function in dependence on the volume and quality of waste water.The control system can be connected to the central computer.