A liquid purification assembly using ultraviolet light irradiation against reproduction of pathogenic microorganisms, comprising - an irradiation chamber (200,300,400,500) having an internal volume and comprising an inlet (204,304,404,504) and an outlet (205,305,405,505), the irradiation chamber (200,300,400,500)comprising - ultraviolet light emitting means (208,308,408,508) configured to irradiate liquid in the irradiation chamber (200,300,400,500) with ultraviolet light, - a first one-way valve (206,306,406,506) allowing the liquid to flow through the inlet (204,304,404,504) into the irradiation chamber (200,300,400,500) when the volume of the irradiation chamber (200,300,400,500) increases, and - a second one-way valve (207,307,407,507) allowing liquid to flow through the outlet (205,305,405,505) of the irradiation chamber (200,300,400,500) when the volume of the irradiation chamber (200,300,400,500) decreases, wherein the liquid purification assembly further comprises - a cylinder (201,301,401,501) closed by a wall (202,302,402,502) at an end, and a mechanism in the form of a mobile piston (203,303,403,503) enclosed in said cylinder (201, 301, 401,501) configured to cause a change in the internal volume of the irradiation chamber (200,300,400,500), the movement of the piston (203,303,403,503) causing the change in inner volume of the irradiation chamber (200,300,400,500) comprised between the piston (203,303,403,503) and the wall (202,302,402,502) closing an end of the cylinder (201,301,401,501). - an irradiation chamber (200,300,400,500) having an internal volume and comprising an inlet (204,304,404,504) and an outlet (205,305,405,505), the irradiation chamber (200,300,400,500)comprising - ultraviolet light emitting means (208,308,408,508) configured to irradiate liquid in the irradiation chamber (200,300,400,500) with ultraviolet light, - a first one-way valve (206,306,406,506) allowing the liquid to flow through the inlet (204,304,404,504) into the irradiation chamber (200,300,400,500) when the volume of the irradiation chamber (200,300,400,500) increases, and - a second one-way valve (207,307,407,507) allowing liquid to flow through the outlet (205,305,405,505) of the irradiation chamber (200,300,400,500) when the volume of the irradiation chamber (200,300,400,500) decreases, wherein the liquid purification assembly further comprises - ultraviolet light emitting means (208,308,408,508) configured to irradiate liquid in the irradiation chamber (200,300,400,500) with ultraviolet light, - a first one-way valve (206,306,406,506) allowing the liquid to flow through the inlet (204,304,404,504) into the irradiation chamber (200,300,400,500) when the volume of the irradiation chamber (200,300,400,500) increases, and - a second one-way valve (207,307,407,507) allowing liquid to flow through the outlet (205,305,405,505) of the irradiation chamber (200,300,400,500) when the volume of the irradiation chamber (200,300,400,500) decreases, - a cylinder (201,301,401,501) closed by a wall (202,302,402,502) at an end, and a mechanism in the form of a mobile piston (203,303,403,503) enclosed in said cylinder (201, 301, 401,501) configured to cause a change in the internal volume of the irradiation chamber (200,300,400,500), the movement of the piston (203,303,403,503) causing the change in inner volume of the irradiation chamber (200,300,400,500) comprised between the piston (203,303,403,503) and the wall (202,302,402,502) closing an end of the cylinder (201,301,401,501).