This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
The following extract from a report by Mr. Rogers Field, M.I.C.E., dated 6th January, 1876, on "Uppingham Sewerage and Private Drainage", gives a striking instance of the passage of sewer-gas through water-traps. He says: "On my examination of the sanatorium, I found that there was a bad smell in two lavatories attached to water-closets situated one above the other. Further investigation showed that this smell did not proceed from the water-closets, but from the lavatory basins, where a decided current of very foul air was coming into the chamber from the unplugged outlet of the basins, and it was found that each basin was connected directly with a pipe which discharged into a partially-closed gully outside the house covered with snow,, and this again into a cesspool. On opening the gully it was axertained that the outlet was properly trapped, and that there was no apparent escape of foul gas, but that the water in the gully (though clear) had a very bad smell. In order to test whether this arose from any passage of foul gas through the trap, clean water was poured into the gully, and this removed the smell. The gully was then examined again after a few hours, and it was found that the water had assumed a very decided smell. The experiment was repeated with the same result, and it appeared that the longer the water was left after it was changed the fouler it got. Moreover, on closing the gully again after the wa: had become foul, the foul current of air returned in the lavatory. There could be no question, therefore, but that the smell arose from the passage of foul air from the cesspool through the water-trap"
To prevent the penetration of these gases into a house, the space of 18 inches in the open air between the gully and the end of the waste-pipe should be provided. It does not necessarily follow that the gully should be placed so as to stand out 18 inches from the wall; there are many ways of providing this space in a neat and satisfactory manner.
Every gully should fulfil the following conditions: -
(1) The shape should be such as will cause it to be self-cleansing and facilitate the passage of the liquids through it, and it must be free from angles or corners; the simpler the arrangement of the several parts the better.
Fig 380 - Green's Soil-pipe Tnterceptor.
(2) It should have a flat base to ensure its stability and permit of its being firmly set
(3) It should have a seal of not less than 2 1/2 inches in depth - that is to say, more than 2 1/2 inches in depth of water must evaporate before the water-seal would Ik' broken.
(4) The entrance should be provided with a grating, opening outwards, to allow the trap to l>e readily cleansed.
(5) The dish or loose cover should be designed to deliver the water rapidly into the gully, so as to prevent the escape of liquid over the sides; the cover must not be set loose upon the gully, but secured with a properly-made watertight joint.
(6) The gully must be set perfectly level and be securely jointed to the drain.
This requirement of an open channel of 18 inches between the end of the waste-pipe and the gully has in recent years led to the bringing out of many excellent forms of channels, which allow of the gully being set close to the wall.
One of the earliest of these was known as Stidder's, the channel and trap being all in one piece, and the channel l>eing covered with a light iron grating to keep out leaves and litter. The trap and channel being all in one piece occasions a little difficulty in making up to old drain-, owing to the cutting required and obtaining bends of suitable curvature. Docking's patent channel is shown in Fig. 381, but in this case the channel is fitted on to a loose P or S trap, which can of course be turned to any angle according to the direction of the drain with which it has to be connected. Fig. 382 show-the "Loco" channel. A greatly improved disconnecting slipper has been introduced by Mr. Sykes, which is shown in Fig. 383 The slipper is made with a spigot outlet to connect into a loose P or 8 trap as required The inlet is socketed to receive an intake piece, which is made with one, two, or three inlet arms to receive the waste-pipes, as 9hown in the plan. The dipper is covered with a galvanized-iron grating, and has a very neat appearance when set
Fig. 381. - Docking's Channel or Waite-pipea.
Fig. 381. - "Loco" Channel for Waste-pipes.
On reference to Plate XIV., it will be seen that such a slipper might be fixed at a to receive the wastes from the bath, lavatory, and clean-water sink, hut that one of the other forms of channel would be quite suitable for fixing at H for the ground floor lavatory, and at K for the butler's-pantry sink. At E upon the plan is shown a gully to receive the waste water from the wash-up sink in the scullery. This gully requires to be of a special type in order to provide for the peculiarly greasy and offensive liquid produced in the washing and scraping of plates and dishes. When this liquid with its particles of food enters the drain, it congeals rapidly, and forms an obstruction from which a serious nuisance will arise unless it is speedily removed. Builders have attempted to cope with this difficulty sometimes by constructing an objectionable cesspool-gully designed to retain the solid mess, the gully being closely covered up, or else by using a very large earthenware gully, which is equally offensive.
Fig. 383 - Sykes's Slipper. etc. for Waste-pipes.