These series of grinder pumps are particularly used in civil and industrial sewage plants. They have been designed to pump the liquid at a high head with a very low capacity. The cutter unit, in a special hard stainless steel, cuts into small pieces of threadlike materials contained in the liquids. As the risk of clogging is avoided small diameter pipes are used. These pumps can be used to lift the sewage of blocks of flats and villas, small isolated areas far from the sewer systems; the sewage of hotels and campsites, in the food and paper industry, and in those particular situations where the installation is often expensive by using a gravity system.