A dry closet comprises a vessel having an open top and provided with a seat member adjacent the open top. A receptacle holding member is positioned within the vessel and includes a lower container receiving portion and an upper, foraminous, portion. A disposable receptacle is positioned on the holding member prior to use. The receptacle includes a container portion, preferably in the form of a closeable box, and a bag portion much larger in volume than the box when extended upwards of the box in unfolded condition. The bag is closed at the bottom and open at its top and is secured at its lower end within the box and forms a water tight receptacle bag within the vessel. A rim portion at the upper, open, end of the bag is placeable over the upper surface of the seat portion at the top of the vessel. The receptacle holding member and receptacle thus divided the vessel into a first, closed, chamber comprising the space between the vessel walls and the receptacle holding member aNd a second chamber having an open top comprising the space within the receptacle holding member. With the receptacle in place, vacuum is applied to the first chamber thus causing the receptacle to be held in place against the foraminous upper portion of the receptacle holding member. During use, the second chamber is ventilated, utilizing a vacuum source. After use, the top area of the bag is folded together and evacuated using the ventilation vacuum source, such that the walls collapse without entraining air in the bag. The bag is then rolled down on itself until it is within the box container. The box container is then closed and sealed and stored for subsequent disposal. The individual closed boxes are preferably stored in larger carriers capable of carrying several used boxes to a disposal site. The invention is particularly suited to marine use since no waste products are discharged overboard and since pumping-out facilities, necessary for use with holding tank devices, are not required ashore.