The water-supply to the closet should be abundant. Every flush of water should be sufficient to carry the contents of the basin through the soil-pipe and the drain into the sewer. The quantity allowed by the Water Companies in London is two gallons, which is barely sufficient for this purpose, unless the form of closet pan is good, and the down-pipe to it of sufficient diameter. Each closet should have a separate cistern, the best being the so-called “water-waste preventer,” by means of which a certain quantity of water, and no more, can be discharged each time the handle is pulled. One of the best of these is shown in Fig 21. When the handle of this is pulled, the whole of the water in the cistern is syphoned out by the syphon and carried down to the water-closet, whether the handle be held down or not.
The amount of fall from the cistern to the closet should not be less than four feet, and the pipe should be free from bends in order to ensure a thorough scouring of the trap and soil-pipe; and the flushing-pipe should have an internal diameter of not less than 1½ inches. It is commonly supposed that a small flow of water, trickling continuously down a closet, tends to keep it clean, and prevent smells; but the water thus used is simply wasted. Others fasten up the handle of valve-closets so as to allow a large flow of water. This does not answer the desired end, and renders the offending person liable to a penalty for wasting water.
Many different forms of water-closet are in use. In all of them the main requisites are that there should be (1) a good flush of water, (2) a rapid removal of the excreta, and (3) no possibility of reflux of gases. The chief varieties of closets are the pan, valve, wash-out, and wash-down closets.
Fig. 21.
Syphon Flushing Cistern.
In Fig. 21 a portion of the bell of the syphon is shown cut out, so as to display the movable plug at the bottom of the cistern. An objectionable feature in most cisterns is their noisiness in use. In the above cistern, the pipe admitting water is carried down to within an inch of the bottom of the cistern, thus ensuring noiseless entry of water.]
Pan-closets (sometimes called double-pan closets) are essentially bad, though largely employed in the past. The construction is shown in Fig 22. Below the conical basin there is a metal pan capable of holding a certain amount of water, the lower end of the basin dipping into this water. By means of a pull-up apparatus the contents of the pan can be tilted into a second larger pan or container, and the bottom of the container is connected by means of a short pipe with a leaden [bowl-shaped symbol] shaped trap, from the side of which the soil-pipe passes out to be carried down to the drain. The arrangement insures the production of nuisance. The container and [bowl-shaped symbol] trap always arrest a certain amount of foul matter; and each time the handle of the closet is pulled up a puff of foul air comes into the operator’s face. Occasionally the [bowl-shaped symbol trap becomes corroded by the filth it contains, and foul gases from the drain escape into the house.
Fig. 22.
Insanitary Pan Closet, showing D Trap below.
Valve Closets differ from the last in having no container, but only a small box containing a movable water-tight valve, exactly fitting the lower edge of the basin (Fig. 23). They are much superior to the pan-closet, but require an overflow pipe in order to avoid accidental flooding of the closet. The overflow pipe should be made with a syphon bend in it, and the flushing of the closet should be so arranged that each time it is performed water enters the overflow pipe. (See Fig. 23.) The trap below the valve should be in the form of a syphon (see under traps, page [179]), as this is not easily fouled. It is preferably made of lead, securely jointed to the soil-pipe and to the valve box of the closet. A lead tray or “safe” is required on the floor beneath a valve closet, in view of accidental spillings or overflow; and this should be provided with an overflow pipe discharging into the open air.