Principles of Slop-Drainage
If domestic slop water is to be dealt with successfully it is necessary—
1. That all waste pipes terminate well above the level of the ground.
This is a point too much neglected by architects, who are very prone to carefully put all waste pipes below ground level, so that any purification of slops without pumping is impossible.
Allowing a fall of, say, 1 in 10, it is evident that for every foot above ground at which a waste pipe terminates it is possible to deliver the waste on to the surface of the ground at 10 feet from the house. Thus the bedroom sink waste at a height of 10 feet above ground level might be made, if so desired, to deliver its waste 100 feet from the house. It is often necessary to take the waste pipes from the first floor over the path surrounding the house. This is easily accomplished without causing any unsightliness by placing an arch over the path. Such arches may be of galvanised iron for a cottage, or of masonry for a mansion, and are soon hidden by creepers.
Figs. [24] and [25] illustrate how this principle may be carried out; in the one case by a rustic arch costing a few shillings, and in the other case by a porch and arcading of a more ambitious description. Fig. [24] is from a photograph of an arch in actual use. Fig. [25] has been furnished by Mr. Cutler.
Fig. 24.—Rustic Arch.
Fig. 25.—Use of Arch for getting Waste Water clear of House.
When pipes are provided with a rapid fall there is little tendency for water to freeze in them, but in severe climates it might be necessary to pack the pipes.
The waste pipes of kitchen and pantry sinks are, in London, almost always below ground level, it being the custom to place the kitchen and offices in an underground basement; and I have known London architects who have provided country houses with similar abominations, so that the sewage of a basement has to be lifted before it can be properly treated. If this evil is to be avoided, it is essential that the waste pipes of kitchen and pantry sinks terminate at least two feet above ground level. This is a minimum, and if a greater fall can be obtained, so much the better. Kitchen and pantry waste is full of dissolved and suspended matter, and a careless cook will throw down the sink enough food to keep a pig or a dozen fowls. This waste is very prone to become offensive, and it is advisable that it be thoroughly strained before flowing away. Not only should the waste pipe have a fixed and immovable strainer below the plug, but a sink basket should be used, and the waste should be still further strained in a manner to be presently described.
2. No stagnation must anywhere be permitted along the line of slop-drainage.
Experimenting upon this point, I have found that stagnant slops become, as a rule, offensive within 24 hours, even when exposed to the air. Thus I tried the experiment of filtering bedroom slops through a trough filled with stones and provided in the middle of its length with a diaphragm reaching from the top to within an inch of the bottom, and having the outlet only an inch or so below the level of the inlet. This caused stagnation and great foulness, which disappeared immediately the outlet was placed at the lowest level, and stagnation became impossible. Soapy water mixed with urine soon becomes foul if allowed to stagnate in traps, but it has never in my experience been foul if poured upon the earth and allowed to soak away. With a good fall and with the outlets of pipes freely exposed to the air, traps are not necessary, and as all forms of traps are but miniature cesspools, this is a great gain. A trap is never possible in an outside metal pipe because of the fear of frost. The abolition of traps is not only necessary, but a very great gain indeed.
3. Slop-water should run in open gutters, and when it has reached a certain distance from the house it should be allowed to soak away as it runs, and take the line of natural drainage of the locality.
This may be effected by means of