Underneath the safe-tray you will find as a rule a trap of some kind, and generally the trap that is found is a D trap, a trap whose name indicates its shape, and which cannot be washed out by the water that passes through it. The pipe from the closet passes so far in it that it dips below the level of the out-going pipe, and thus forms a sort of dip-trap. The pipe which is the inlet from the closet is not placed close to the edge, but a little way in, to form a receptacle for all kinds of filth!
You will see it is impossible for the water that passes through it to clear the contents out, so that the trap is simply a small cesspool, nothing more nor less. Into that trap various waste pipes are frequently connected.
There is another form of D trap in which there are two waste pipes going into the water near the bottom of the trap (probably the waste pipe of the safe and the waste pipe of the cistern).
The D trap, then, is a bad form of trap, because it is not self-cleansing. The water cannot possibly keep it clear of sediment. So that some trap should be used which is self-cleansing, and the water which passes through it is capable of keeping it clean. Now that trap is a mere ∾-shaped bend in the pipe, to which we give the name of siphon, not because we want it to act as a siphon—for if it acts as a siphon it is of no use!
A curious thing about siphon traps and pan closets is, that the form of trap which was used first in connection with water-closets was the siphon trap, which we now praise; and the form of trap which supplanted it was the D trap, which we are now condemning and taking out wherever we can. A still more curious thing is that the form of water-closet which we now condemn (the pan closet) was the form of closet which supplanted the closet we are now using (the valve closet). The valve closet was invented long before the pan closet. Bramah valve closets fixed forty years ago often act tolerably well now, and at the present day they are only taken out because they are really actually worn out.
The valve closet, which we often find upstairs in old houses instead of the pan closet, has no large iron container under the seat, but it has a water-tight valve under the basin, and so requires a small valve-box; so that there is no great collection of foul air immediately under the basin of the closet. The valve closet, however, has a disadvantage in that it requires an overflow pipe; because the valve is water-tight, and if servants throw slops into it, or the supply pipe to it leaks, the water goes on running and the basin fills, and, if there were no overflow pipe, it would overflow on to the floor; so that probably the pan closet ousted the valve closet because it was found that people could go on throwing in any amount of slops and using it in the roughest manner without getting their ceilings damaged. However, the valve closets, as they were originally made, generally had overflow pipes which went into part of the apparatus below. Occasionally these overflow pipes are connected with soil pipes or the trap of the closet below, but these are exceptional instances.
One of the water-closets in the basement is very frequently in an exceedingly improper position—either in the scullery or actually in the kitchen. These w.c.’s ought all to be outside the house.
If closets are in the middle of the house they ought to be done away with, and should be put against an outside wall. This might be done by sacrificing a bit of some room which can be spared, or by converting some small bedroom into a bath-room and closet, or still better, by making a sort of tower outside the house.
The merits and demerits of the various kinds of water-closet were discussed in a paper by Emptage before the Congress of the Sanitary Institute at Glasgow. To be rightly considered wholesome and adapted for general use, a closet should, in Emptage’s opinion, possess the following qualifications:—