To enable the pumping, filtering, sterilization, and oxygen supply of the water inside of a compact water tank, and to reduce the economical and physical burden in comparison with the conventional one by supplying the pressurized air from an air pump arranged outside of the compact water tank.

A pumping pump formed of a pumping pump main body 3 and a water guide pipe 7 is fixed to the inside of a compact water tank 6, and the pressurized air from an air pump 1 arranged outside of the compact water tank 6 is continuously supplied to an air supply port 11 positioned under the water guide pipe 7 through an air feeding pipe 2A, and the water inside of the water guide pipe 7 is continuously pumped so as to continuously pump the water inside of the compact water tank 6, and furthermore, oxygen can be sufficiently supplied. A filtering part and a sterilizing part are formed inside of the pumping pump main body 3 so as to filter and sterilize the water inside of the compact water tank 6 and the water can be always maintained clean.