Submersible sludge pumps destined for pumping fresh and slightly polluted water and sludge containing solids of non-abrasive character up to the size 5mm, as well as long fibrous stuffs of organic origin, odds and ends without abrasive solids, thick strings and cords, and synthetic fibres, and so on. Pumps are advantageous to waste water treatment plants, pumping from overground and underground resources (rivers, ponds, pools, cellars, water wells, etc.). They were designed for versatile applications by reason of sufficient capacity, weight and manufacture qualities. On request it is possible to supply them with a float.