The next question is that of the baths, lavatories, and sinks, which it is necessary should be constructed in such a manner as will allow of themselves and their surroundings being kept thoroughly clean and wholesome, provision being made to allow of regular inspection for cleansing purposes, when these fittings are enclosed in woodwork; though it is much to be preferred, from a sanitary point of view, that they should be fixed without enclosures, especially sinks, and they should also be clear of all angles and ledges where filth is likely to accumulate.
The oudet fittings to these appliances should be of the description known as full-way fittings, having an area of space through the holes of their grates equal to or slightly larger than the bore of the waste pipes fixed to them, so as to ensure such waste pipes being thoroughly flushed and scoured by each flush sent down them, bath and sink waste pipes being not less than 2 inches in diameter, and those of lavatories 1 1/4 inch, with traps fixed immediately underneath the appliances, and properly ventilated to prevent syphonage.
Although the legitimate use of a bath is to cleanse the human body, its discharge of from 30 to 50 gallons of water can be utilised with great advantage as a flushing force for cleansing the drains, as hereinbefore explained, and for this reason the bathroom should be situated as near as possible to the point where the discharges therefrom will act on the whole drainage system, the benefit of which is obvious to all; and to utilise this force properly, it is absolutely necessary that full-way fittings and pipes be used, and the waste made to deliver in the open air on to a proper disconnecting trap similar to Fig. 1002, but with no inlet - the waste water discharging on to the grating; and this same form of gully should be used to secure lavatory or sink discharges, excepting the case of the latter having large discharges of grease likely to choke the drains, when a proper grease trap should be fixed in a position far enough away, or sealed in such a manner as not to be offensive; but, where there is not sediment enough to require such an appliance, it should be flushed clean through the above trap and into the sewer.
The ordinary yard gully is an appliance totally unfitted for the purpose of receiving discharges from baths, lavatories, and sinks, as it is more of a filth-collecting and retaining appliance, which throws off injurious emanations from the decomposed matter which it contains; and, moreover, when fixed outside, they are usually in such close proximity to the house as to allow these noxious gases gaining admission thereto, and then they become, practically speaking, small cesspools about a house. Anti-bell or adjustable traps (as Figs. 1003 and 1004) should always be used, the latter, as the name implies, being capable of regulation according to circumstances of fall, etc.
In dry seasons and hot weather it is essential that the gullies, whether from waste or rain pipes, should be frequently supplied with water to maintain the proper seal, which is easily dried up, and becomes a great source of danger. A sanitarian's aim in arranging sewerage work should be to avoid stagnation and the consequent accumulation of foul gases by so arranging the pipes that a constant current of fresh air can be maintained in every pipe and drain, including wastes, overflows, soil pipes, etc., giving the principle of diffusion its fullest extension, and at the same time taking care that in no case shall any waste or other such pipe act as an inlet ventilator to the building.