The invention relates to an irradiation chamber (300) for a liquid purification apparatus using ultraviolet light irradiation against the reproduction of pathogenic microorganisms, comprising an inlet portion (302), an outlet portion (303), and a main portion (301) having an elongated shape, the irradiation chamber (300) having an internal surface defining an cavity, the irradiation chamber (300) being provided with ultraviolet light emitting means configured to irradiate liquid in the irradiation chamber (300) with ultraviolet light, the main portion (301) having a shape enlarged compared to the inlet portion (302). The internal surface of the irradiation chamber (300) defining the cavity is a three dimensional rounded surface, having no edge which forms a recess. The invention also relates to a liquid purification apparatus and to a beverage dispenser.