Abstract: A water filtering device can comprise: a filter, an optional prefilter, and two stages pumping system with recirculation circuit is disclosed. The pumping system is formed with two pistons, merged together where the recirculation piston is further equipped with at least one non-return valve. During the intake phase, the chambers are filed through the pair of non-return valves, while the concentrate and the feedwater are mixed through the non-return valve. During the compression, the valve is closed, and the pressure generated by the piston within the chamber is transmitted to the chamber and subsequently towards the filtering means. Permeate is extracted out while the concentrate is sent to the chamber by the recirculation. The system can achieve pressure sufficient for ultrafiltration, nanofiltration or reverse osmosis of any water type available.

Abstract: A simple to operate personal water purification device using membrane type filtration with almost constant pressure exerted to the membrane filter during the operation. The water inlet is connected to the high pressure chamber via a non-return valve. The water from the chamber is injected via the piston into the already pressurized circuit which maintenance filter working pressure. A pressurized circuit is formed in the concentrate cylinder and the filtration unit. The fluid circulation within the pressurized circuit is enabled via motion of a circulation piston. The permeate outlet produces potable water while the remaining concentrate is returned to the return chamber. The circulation piston and high pressure piston are connected via piston coupling and operated, preferably, by hand activating reciprocal motion of the piston rod. The membrane type filtration can be a ultra-filtration membrane, a nano-filtration membrane or a reverse osmosis membrane.

Abstract: A simple to operate personal water purification device using membrane type filtration with almost constant pressure exerted to the membrane filter during the operation. The water inlet is connected to the high pressure chamber via a non-return valve. The water from the chamber is injected via the piston into the already pressurized circuit which maintenance filter working pressure. A pressurized circuit is formed in the concentrate cylinder and the filtration unit. The fluid circulation within the pressurized circuit is enabled via motion of a circulation piston. The permeate outlet produces potable water while the remaining concentrate is returned to the return chamber. The circulation piston and high pressure piston are connected via piston coupling and operated, preferably, by hand activating reciprocal motion of the piston rod. The membrane type filtration can be a ultra-filtration membrane, a nano-filtration membrane or a reverse osmosis membrane.