In the forms of w.c. already described, clean water is used for flushing, and we have seen that two gallons, the quantity usually allowed, does not suffice for this purpose, unless the closet pan is of the best possible shape, and the service pipe sufficiently wide to project the water by means of a rim-flush forcibly over the pan and into and beyond its trap. Other forms of w.c. have been employed of which the most important are slop-water closets, and trough-closets.
In Slop-Water Closets the waste water from sinks and baths is utilised for flushing, and thus a saving of water is effected. This form of closet is used considerably in manufacturing districts, and is less liable to freeze than an ordinary w.c. The sink discharges on to a gully in the usual manner, but the outlet of this gully is connected with a tilting vessel or tipper, holding 3½ gallons in Duckett’s closet, which is the best known of this type. The tipper is balanced on brass bearings, and tips over when full, discharging its contents into the closet trap, which is thus flushed. The slop-closet is a great improvement on the privy-middens or pail-closets, which in some towns it has superseded, but is not so cleanly as an ordinary w.c.
Trough Closets are also known as “latrines.” The best type consists of a glazed earthenware trough under a series of w.c. seats. The trough is slightly inclined towards the outlet, at which is a weir, beyond which is a trap. An automatic flushing tank connected with the upper end of the trough and five to six feet above it, discharges water at intervals and drives the fæcal matter over the weir and through the trap. This form of closet is only suitable for factories. It is to be deprecated for schools, and even for factories, unless there are exceptional reasons for its continuance, as fæcal matter possibly of an infectious character may be retained a considerable time in the trough.
The domestic Slop Closet or “housemaid’s sink” must not be confused with slop-water closets mentioned above. The slop-closet or sink is used for emptying the contents of bedroom pails. These being necessarily foul and liable to early putrefaction must be treated exactly like other sewage matters. An ordinary pedestal w.c. with a lift-up seat answers excellently as a slop-closet; but in large houses and public establishments a separate slop-sink is desirable with a larger surface than most water-closets. The slop-closet must be connected with the soil-pipe, just in the same way as a w.c.
Fig. 29—Section through a House from Front to Back shewing Drainage Arrangements.
A.—Sewer; B.—Intercepting trap; C.—Cleaning eye for pipes between chamber and sewer; D.—Inspection chamber; E.—Inlet ventilator; F.—Gully-trap for forecourt; G.—Air-bricks for ventilation under floors; H.—Damp-proof course[8]; I.—Concrete 6” thick over site of house; J.—Drain, fall 1 in 24, imbedded in concrete; K.—Soil-pipe carried up full size above eaves; L.—Upstairs w.c.; M.—Gully-trap receiving water from N scullery-sink, O bath and P rain-water stack-pipe; S.—Ventilating pipe at upper end of drain; T.—Pipes leading to same.
The soil pipe is the vertical pipe carrying the contents of the water-closets in the drain. It must be distinguished from the drain, which is chiefly, if not entirely, underground. The exact position of the soil-pipe and its relation to the drain can be seen in Fig. 28 and 29, which should be carefully studied. The soil-pipe should be made of drawn lead without seam, of uniform thickness throughout, and of at least 7 lbs. or better 8 lbs. weight per superficial foot. Any joints in the lead pipe should be of the kind known as “wiped,” not a “slip” joint. The outside of a wiped joint is shewn in Fig. 30B. Iron pipes if used must be 3 ∕ 16 inch thick, and have sockets sufficiently wide and strong to permit of the joints being caulked with molten i.e. “blue” lead, in the same way as water-mains are laid.
The soil-pipe should be throughout its course under observation. It should not be built into a wall, where it might be accidentally pierced by nails, nor within the house, allowing foul gases to escape from weak points in the joints. It should be carried through the wall of the house immediately beyond the closet trap.
The soil-pipe should not be more than four inches in diameter. It should be continued from its highest point at the junction with the closet-trap above the roof by a pipe of the same diameter, with its end wide open (Fig. 29 K). This ventilation of the soil-pipe is essential (a) to prevent the entry of foul effluvia into the house, especially when the water in the closet-trap is dried up; (b) to prevent unsyphoning of the upper by the lower water-closets in a house. (On this point see p. 172).