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.
In towns which have a constant water-supply, cisterns for dietetic purposes not needed, and where one is found, it is better to advise its total disuse than to suggest a change from a lead cistern to one of another substance. Cisterns in such towns should only be used in connection with hot-water terns; and even in these cases, the cold-water taps in kitchens, sculleries, and butlers pantries, should be supplied direct from the street mains. When the supply is intermittent, and storage of drinking-water therefore a necessity. the cistern used for the purpose should not be connected with the circulation-system, but should be a separate cistern, composed of a non-metallic material, and placed in an easily-accessible position on the ground-floor.
Although there may be no necessity to use the cisterns of the circulation-system for drinking purposes, it is requisite that they be protected from pollution. Their position and surroundings, and the pipes connected with them, must therefore receive the attention of the Inspector. With regard to the first two he may have little power of control, but when a cistern is found beneath the floor of a bedroom, or in a roof-loft opening from an attic bedroom, - both being positions within the writers experience, - perhaps a notice requiring removal to a more suitable position might be successfully enforced. The cisterns ought to be placed in a room suitably prepared for the purpose, and used for that purpose only. The room should be floored, lighted, plastered, ceiled, ventilated, and be easily accessible. The cistern should be covered with a lid projecting beyond the sides, and slightly raised above the edges of the cistern on small wood blocks placed at intervals on the underside of the cover.
There should be no pipes connected from the cistern directly to a w.c. urinal, or housemaid's sink. The overflow-pipe should not be joined to any other, but be carried through the nearest wall so as to discharge in the open air. An overflow-pipe is only in use when a defect occurs in the ball-tap, which permits the water constantly to run. This may not happen for years, and therefore, on account of evaporation, no water-sealed trap can be relied upon for safety when the overflow is connected to another waste-pipe. A copper flap on the outer end of the overflow-pipe is useful to prevent dust being blown through into the cistern.
Another kind of overflow, found mainly in cisterns of older make, is called standing waste", and consists of a hollow brass plug fitting into a socket in the bottom of the cistern; to the upper part of the plug is soldered a lead pipe, brought up to the intended water-line, and left open at the top to receive the overflow of water. From the socket downwards is continued a waste-pipe, discharging in some cases near a yard-gully, and in others into soil-pipes and drains. It will be seen that, by grasping the overflow-pipe where it emerges from the water, and giving it a pull upwards, it and the plug at its base may be raised from the socket in the bottom of the cistern, allowing the water to be emptied through it. A standing waste is not an absolute necessity, because the cistern may be nearly emptied through the bath and other taps, as the pipe to the boiler [a fixed within about two inches from the bottom. But after scrubbing the cistern, this remaining water, with the dirt, must be mopped out, whilst the standing waste permits the escape of the entire contents.
There can be no objection to a standing waste used solely as such, but there is grave reason why it should not also be used as an overflow. To connect such a waste to a drain or soil-pipe is a legal offence, - i.e. it constitutes a nuisance under the Public Health Acts, - even where it is not used as an overflow. But even where it is not so connected but discharges into or near a yard-gully, some unnecessary danger exists, when the top is left open in the cistern, because of the possibility of gases, arising from decomposable matter in the gully, passing up the pipe, and thus being brought into contact with the water in the cistern, and perhaps also diffused through the house.
Fig. 667. - Standing Waste in Cistern.