SANITATION OF BUILDINGS. To preserve the health of the occupiers of any building, it is imperative that all polluted water and solid organic refuse should be removed from the premises at frequent intervals. Where the buildings are in a town it is usual for the local authority to remove the solid dry refuse by carting, but where a public water supply is available, liquid wastes are flushed away through a system of pipes. These latter com prise waste pipes to carry washing water, soil pipes to carry human excreta and rainwater pipes. If such pipes pass under the grounds of the premises they are termed drains and usually discharge eventually into the sewers in the public highway or into cesspools or septic tanks.
Drains.—Outside drains are usually composed of glazed stone ware or vitrified earthenware pipes, 2 ft long, not often larger than 4 in. diameter for branches and 6 in. diameter for the main drain. All drains inside a building, whether under or above ground, are usually of iron pipe. If the pipes are cast iron the joints are caulked with oakum and molten lead. If of wrought iron or steel they are screw joints.
All drains that carry solids should be provided with accessible clean-out caps, which can be readily unscrewed for the admission of cleaning rods, to remove obstructions which may choke the drains. It is good practice to have a clean-out cap or plug at each change in direction of a drain pipe. The drains must be run straight between these clean-out points.
If the chamber is in an isolated position, the cover, which should be of cast iron, may be provided with a grating to afford means of ventilation, otherwise the chamber is fitted with a ven tilating pipe to form a fresh-air inlet, and this is carried up well above ground level to some position where an accidental emission of drain gas would not cause a nuisance. Any such chamber should be built of the best bricks or cement concrete, suitably provided with curved channels for the branch connections. Such channels may be formed in the concrete or composed of half round glazed pipes. Where inspection at bends is required, or where branches meet, but where it is considered to be too expen sive or unnecessary to build a chamber, a shaft of 6 inch pipes is sometimes substituted, the whole being carefully jointed and sup ported by concrete. Since complete access to the drain is then im possible, the inspection will be confined to locating the position of a blockage or leakage to any particular length of pipes. When there is any possibility of the drains being flooded by the sewer, special interception traps are used in which a floating ball seals the inlet, and so prevents the reversal of the flow. No traps in which hinged valves or other mechanical contrivances are made use of, should be allowed.
In American plumbing practice all soil and waste stacks are usually installed within the buildings to prevent them from be coming frozen. These stacks generally are connected at their base to a system of iron main drain and branch drains in the basement, either at the basement ceiling or under the basement floor. In some cities, it is compulsory to have a main drain-trap with a fresh air inlet pipe located at the point where the main house-drain leaves the building to disconnect the house from street sewer gas, and to insure a proper ventilation of the house drainage system.