_The Pail System_ is an economic, simple, and, on the whole, very efficient method of removing fresh excreta. The excreta are passed directly into stone or metal water- and gas-tight pails, which, after filling, are hermetically covered and removed to the places for final disposal. This system is in use in Rochedale, Manchester, Glasgow, and other places in England.
The pails may also be filled with dried earth, ashes, etc., which are mixed with the excreta and convert it into a substance fit for fertilization.
_The Pneumatic System_ is a rather complicated mechanical method invented by Captain Lieurneur, and is used extensively in some places. In this system the excreta are passed to certain pipes and receptacles, and from there aspirated by means of air exhausts.
=The Water-carriage System.=--We now come to the modern mode of using water to carry and flush all sewage material. This method is being adopted throughout the civilized world. For it is claimed a reduction of the mortality rate issues wherever it is introduced. The water-carriage system presupposes the construction and existence of pipes from the house to and through the street to the place of final disposition. The pipes running from the house to the streets are called house sewers; and when in the streets, are called street sewers.
=The Separate and Combined Systems.=--Whenever the water-carriage system is used, it is either intended to carry only sewage proper, viz., solid and liquid excreta flushed by water, or fain water and other waste water from the household in addition. The water-carriage system is accordingly divided into two systems: _the combined_, by which all sewage and all waste and rain water are carried through the sewers, and the _separate_ system, in which two groups of pipes are used--the sewers proper to carry sewage only, and the other pipes to dispose of rain water and other uncontaminated waste water. Each system has its advocates, its advantages and disadvantages. The advantages claimed for the separate system are as follows:
(1) Sewers may be of small diameter, not more than six inches.
(2) Constant, efficient flow and flushing of sewage.
(3) The sewage gained is richer in fertilizing matter.