Part 4

Rainfall varies exceedingly in different places, and even in the same situation it is impossible to foretell the amount to be expected during any short period of time, but the most careful observations show that about 4 ft. in depth descends at New York and vicinity every year, or nearly 1 in. a week. If this amount were to be furnished uniformly every week, the size of a cistern need only be sufficient to contain one week’s supply, but we often have periods of 4 weeks without receiving the average of one, and we must build accordingly.

The weekly average of 1 in. equals 1 cub. ft. upon every 12 ft. of surface, or 3630 cub. ft. upon an acre, weighing about 113 tons. Upon a roof 40 ft. by 40 ft., 1600 sq. ft., it would be 133 cub. ft., 1037 gal., or about 26 barrels of 40 gal. each. A cistern 8 ft. across and 10 ft. deep would contain 502 cub. ft.; and one of 10 ft. across and 10 ft. deep, 785 cub. ft., or 6120 gal.--about the average fall upon a roof of the above size for 6 weeks; while the smaller cistern would hold 3900 gal., or a little less than 4 weeks’ rainfall. The weekly supply of 1037 gal. is equal to 148 gal. per day, or nearly 15 gal. to each individual of a family of 10. This is certainly enough, and more than enough, if used as it should be; but where water is plentiful it is wasted, and in our capricious climate, whether we depend upon wells or cisterns, it is wise to waste no water at all, at least during the warm summer months, and lay by not for a wet but a dry day. For this country, Field estimates 2-3 gallons of tank capacity for every square foot of roof area.

In Fig. 3 _a b c d_ show the excavation that must be made for the cistern, and supposing the diagram to exhibit, as it does, a section of the cistern, the receptacle for the water will be, when finished, taking the relative proportions of the different parts into consideration, just about 9 ft. wide and 4½ ft. deep. Of course, the excavation must be made greater in breadth and depth than the dimensions given, to allow for the surrounding walls and the bottom. The walls may be of brick, cemented within, and backed with concrete or puddled clay without, or of monolithic concrete; but the bottom, in any case, should be made of concrete. The trench _e f g h_ running across the bottom of the cistern is 2 ft. broad and 2 ft. deep. In the middle of this opening is built up a 9 in. brick wall, or a party-wall of concrete, _i k_. Along the bottom of the wall openings _l_ are left at intervals. The party-wall divides the entire space into the larger outer cistern _m_, and the smaller inner cistern _n_. Supposing the breadth from _e_ to _f_ to be 2 ft., and the wall 9 in., spaces of 7½ in. will be left on each side of the wall. These are filled to ¾ the height, or for 18 in., with lumps of charcoal, smooth pebbles, 1-3 in. in diameter, being laid along the top of the charcoal till the trench is filled up. The cistern is so constructed that the water from the roof enters _m_; it passes downwards through the stones and charcoal, as shown by the arrow at _f_, goes through the opening and forces its way upwards in the direction of the arrow at _e_ into the cistern _n_, in which it rises to the level of the water in _m_, to be drawn thence for use by a small pump.

Various modifications of this form of tank-filter will suggest themselves to readers possessing any mechanical genius. The great point is to prevent contamination from the soil by using good material and making sound work. Further, the overflow pipe of the tank must not communicate with any drain or sewer.

Recently several inventors have introduced apparatus for separating rain-water from impurities. One of these, bearing the name of Roberts, is illustrated in Fig. 4. Its principle of action is to reject the first portion of the rain which falls (as it is this which chiefly washes the dirt off the roof), and only to collect the latter portion of the rain. The water from the roof first runs on to a strainer, that intercepts rubbish; it then passes through one of two channels in the upper part of the canter, balanced upon a pivot. At the commencement of a shower, the canter is raised in the position shown in Fig. 4, “running to waste,” and the bulk of the water passes through a channel which directs it into the lower or wastewater outlet. Meanwhile, a very small proportion of the water is accumulating in the lower part of the canter, very slowly in light rain but more rapidly in heavy rain, so that it is filled up by the time the roof has become clean. Then the weight of water causes it to fall down as shown in Fig. 4A “running to storage,” so that the clean water may run through the upper storage outlet pipe. This very useful little apparatus is made and sold by C. G. Roberts, Collards, Haslemere, Surrey.

Perhaps this affords as good an opportunity as any of drawing attention to the highly artistic rain-water heads that have lately been introduced by Thomas Elsley, of 32 Great Portland Street, W. These are made to suit every style of architecture and every variety of roof and guttering, and practically without limit as to size. Their quality is beyond praise.

It is essential to bear in mind that rain-water is liable to exert considerable solvent action on lead, consequently pipes and cisterns of this metal must be avoided. The pipes may be of iron, or of specially lead-encased block-tin, and the cisterns of “galvanised” iron or slate.

As Eassie has pointed out, there is much to be considered in the arrangement of rain-water pipes from a sanitary point of view, where a separator and storage tank are not in use, because the foul air delivered from them is sucked into the rooms near the roof, on which the sun’s heat pours. A fire lighted in a room develops the same danger when the rain-water pipe terminates near the windows of the room. Another danger accruing from rain-water pipes which connect directly with the drain is due to the fact that the joints of the iron rain-water pipes are seldom air-tight, and foul air is therefore often driven or sucked into the rooms when the windows are open. It is easy to imagine how dangerous this must be in houses which have been fitted up with iron (or even lead) rain-water pipes running down the interior walls, and having their terminations close to a dormer window, skylight, or staircase ventilator on the roof, with the foot of the rain-water pipe taken direct into a drain leading to a town sewer. But the risk is greatly increased when the rain-water pipes are connected with a closed cesspool, to which the rain-water pipe is acting as a ventilator.

When rain-water pipes deliver into the drain directly, they are often made to act as soil pipes from the closets, in which case the evil is intensified. The soil from the closets is apt to adhere to the interior of the pipe, generally on the side opposite to that traversed by the rain-water, and the poisonous smell escapes at any bad joints and always at the roof orifice.

When the rain-water pipe is of cast iron, other sources of danger are present if the pipe is used also for conveying soil from a closet. Unless the rim of the soil pipe from the closet is joined to the rain-water pipe by a proper cast-iron socketed joint, the connection must be made by means of a piece of lead pipe which receives the soil pipe, and the joint between the lead soil pipe and the upper and lower parts of the cast-iron pipe cannot be properly soldered. Here sometimes grievous calamity follows cases where the combined pipe is ventilating the drain and sewer; the pipe joints are frequently open, and when the windows are unclosed for ventilation the foul air is whisked into the house. Eassie insists that it is cheaper to owner and dweller alike to have a separate soil-pipe erected at first.

All rain-water pipes should deliver into the open air, and have no connection with the drains, except when they are disconnected. They should discharge their contents over a gully grating as at _a_, Fig. 5, or underneath the grating as at _b_, the ends of the pipes in both cases being in the open air. Every householder should insist upon this being carried out. But occasionally the rain-water pipes descend inside the house and there is no open yard where a disconnecting gully can be fixed. In such a case a separate drain should be laid to the nearest area or yard, and separation ensured. In laying down new drains in a house, where the rain-water pipes must descend in the interior, it will be better to provide a separate or twin drain to the nearest open-air space.

Provision must be made at the roof for keeping foreign matters out of the rain-water pipes. Leaves, soot, and dirt will accumulate round the pipe orifices, and very often will cause the gutter to be flooded during a storm. The usual way to avert this is to fix over the opening of the pipe in the bottom of the gutter a galvanised open wire half-globe, or a raised cap of thick lead pierced with tolerably large holes. The cost for this is trifling, but the value is great. Whenever rain-water pipes _must_ run down the inside wall of a house, lead should be adopted. Sometimes rain-water pipes are taken down in the interior, when a very little initial study could have brought them to the exterior face of a wall--where alone they should be taken, whenever it is possible to do so.

On attic roofs, and where only one side of the house can be used for the attachment of rain-water pipes, the water from one side is brought across the roof by means of a “box” gutter of wood, lined at the bottom and sides with lead or zinc, and covered with a board. This often emits a very foul smell, owing to the accumulation of decaying matter. When such guttering cannot be avoided, it should occasionally--say once a week--be carefully cleaned out. The same matters will sometimes silt up and stop the gullies, shown at the foot of the rain-water pipes (Fig. 5), hence it is equally necessary to see that these traps are cleaned out, say monthly.

Rain-water pipes are often made the waste pipes of lavatories, baths, sinks, and slop-pails. When properly disconnected at the foot, in the open air, and when the top of the rain-water pipe does not terminate under a window of an inhabited room, this does not much matter; but when the court-yard is limited in area, and there is a window belonging to a living or sleeping room just overhead, where the rain from the roof delivers itself into the upright pipe, an offence will arise from the decomposing fats of soap, which form a slimy mess adhering to the interior of the pipe, that no amount of rainfall will dislodge.

_Cisterns._--Cisterns should be in a cistern-room if possible, but, at all events, placed where they can be got at, covered over with suitable fittings, and ventilated to the open air. A drinking-water cistern should never be placed in a water-closet, for no amount of disconnection in such a case will suffice to counteract its evil surroundings. Neither should it be placed in a bath-room, which is liable to a steam-laden atmosphere. Nothing can be said against a site out of doors, on the flats, or below (if away from dustbins and ash-heaps); but in such cases the cistern, with its service pipes, should be well protected from frost. The position of a cistern should be equally carefully chosen no matter whether the supply be constant or intermittent, or whether there be a high or a low pressure cistern. And not only should it be made certain that the “standing waste” pipe of the cistern delivers in the open air, but that any “overflow” pipe of the cistern delivers in like cleanly fashion. It is too common to take these wastes down to the nearest sink. It might prove expedient to thus disconnect a cistern waste when time presses, and when the alternative is costly, but the practice is not to be commended.

Eassie’s strictures with regard to cisterns apply equally to those feed cisterns which supply hot-water circulating cisterns or boilers where water is heated for kitchen, scullery, still-room, or bath-room uses. It is too common to find the feed cistern, which is the small iron cistern that automatically keeps the kitchen or other basement boiler full, placed in the darkest corner of the commonest stowaway cupboard, with its overflow pipe joined to the drain.

The materials of which cisterns are constructed vary much in town and country. In old houses will be frequently found cisterns formed of slabs of stone, just as they have been raised from the quarry, and sometimes of slabs of rough slate, and than these, provided they are regularly cleaned out and the waste pipes disconnected, probably no better basement cistern could be found. The same might perhaps be said of brickwork cemented inside. Cisterns composed of slate possess a drawback in their weight, which sometimes prevents them from being adopted upstairs. It has become a frequent practice now to have them enamelled white inside, so that the slightest discoloration of the water, or sediment at the bottom, can be instantly detected.

Cisterns composed of metal throughout embrace old cisterns of cast lead, dated early in the 18th century; these are quite harmless, on account of their natural silver alloy, and they may be trusted, all other conditions being satisfactory. Cast-iron cisterns, made of plates bolted together, if kept full, and not subject to rust, are unobjectionable. Wrought iron, which has afterwards been “galvanised,” is a very common form of cistern, and appears to be the cheapest. Little can be said in its disfavour, although experiments made in America have proved that some waters attack the inner coating. The commonest form of cistern is composed of wooden framing lined inside with sheet lead. This is not the best for storing drinking-water, and slate would be preferable; but no one would say that all water drawn from leaden cisterns would injuriously affect health. The interior of a lead-lined cistern will be found to acquire a whitish coating, and it is due to this chemical alteration of its surface that the contained water can be drunk with more or less impunity. Nevertheless, there are some waters which very readily attack lead, and care should be exercised in this respect. In cleaning out a lead cistern the surface should never be scraped, but simply washed down with a moderately hard brush. Sometimes houses are provided with zinc-lined wooden cisterns; this metal for several reasons is one of the worst materials for water storage, and should never be used for drinking-water. Neither should wooden butts or barrels be employed for storing water anywhere in a house, as they speedily become lined with a low vegetable growth detrimental to health.

A great mistake consists in storing away a great quantity of water in abnormally large cisterns, in consequence of which the tap is drawing off for a very long period the water first delivered to it, and which is not the cleanest water. This does not so much matter in cisterns which supply closets or baths, but it is reprehensible when the water is for the bedroom decanter and the nursery.

_Pipes._--Pipes for conveying water are generally of lead, because it is more easily bent than any other metal; but frequently iron pipes are substituted when the water main has to be brought from a great distance. Eassie remarks that the conveyance of some waters in long lengths of leaden pipe, in which the water must necessarily stand, and the use of leaden suction pipes in wells, is not a thing to be looked upon with great favour. Hence it is that galvanised iron pipes are used by some, and in the case of water conveyance from a long distance, the cast-iron pipes coated inside with Dr. Angus Smith’s solution, or subjected to the Bower-Barff system of protection against rust, are now very largely adopted. Glass-lined pipes of the American pattern have also been introduced into this country, but have not yet made much headway, which is a pity, seeing that glass forms the best of all conduits for water. Much depends upon whether the water is of such a character as to rapidly decompose lead.

Leaden pipes, of sufficient weight per lineal foot, may fitly conduct the flushing water for closets and the cold water to baths and lavatories; but what is called “lead-encased block-tin pipe” should be used in conveying water from the separate drinking-water cistern. The cost is some 50 per cent. more than for leaden pipe, and there is more difficulty in making the joints, but these points are overbalanced by the certainty of non-pollution of the water. Water pipes should be fixed in separate wall chases, easy of access. Service pipes should also be kept separate from each other, and provided with proper stop-cocks in case of accident.

_Pumps._--It will not be out of place here to offer a few remarks on the construction, capacity, and working of the 3 kinds of common pump in everyday use--i.e. (1) the lift-pump; for wells not over 30 ft. deep, (2) the lift and force, for wells under 30 ft. deep, but forcing the water to the top of the house, and (3) the lift and force, for wells 30-300 ft. deep.

The working capacity of a pump is governed by the atmospheric pressure, which roughly averages 15 lb. per sq. in. It is also necessary to remember that 1 gal. of water weighs 10 lb. The quantity of water a pump will deliver per hour depends on the size of the working barrel, the number of strokes, and the length of the stroke. Thus, if the barrel is 4 in. diam., with a 10 in. stroke, piston working 30 times a minute, then the rule is--square the diameter of the barrel and multiply it by the length of stroke, the number of strokes per minute, and the number of minutes per hour, and divide by 353, thus:--

42 in. × 10 in. stroke × 30 strokes × 60 minutes ------------------------------------------------ 353

= 815 gal. per hour. About 10 per cent. is deducted for loss. The horse-power required is the number of lb. of water delivered per minute, multiplied by the height raised in ft., and divided by 33,000. Thus:--

815 gal. × 10 lb. × 30 ft. lift ------------------------------- = 7·4 H.P. 33,000

Fig. 6 shows a vertical section of the simple lift-pump. _a_ is the working barrel, bored true, to enable the piston or bucket _b_ to move up and down, air-tight. The usual length of barrel in a common pump is 10 in. and the diameters are 2, 2½, 3, 3½, 4, 5, and 6 in.; a 3 in. barrel is called a 3 in. pump. The stroke is the length of the barrel; but a crank, 5 in. projection from the centre of a shaft, will give a 10 in. stroke at one revolution; but in the common pump shown, use is made of a lever pump handle, whose short arm _c d_ is about 6 in. long, and the long arm or handle _d e_ is usually 36 in., making the power as 6 to 1; _f_ is the fulcrum or prop. Improved pumps have a joint at _f_, which causes the piston to work in a perpendicular line, instead of grinding against the side of the barrel. The head _g_ of the pump is made a little larger than the barrel, to enable the piston to pass freely to the barrel cylinder; in wrought-iron pumps, the nozzle is riveted to the heads, and unless the head is larger than the barrel these rivets would prevent the piston from passing, and injure the leather packing on the bucket. The nozzle _h_, fixed at the lower part of head, is to run off the water at each rise of the piston. There is 1 valve _i_ at the bottom of the barrel, and another in the bucket _b_.

The suction pipe _k_ should be ⅔ the diameter of the pump barrel. A rose _l_ is fixed at the end of the suction pipe to keep out any solid matter that might be drawn into the pump and stop the action of the valves. The suction pipe must be fixed with great care. The joints must be air-tight: if of cast flange-pipe, which is the most durable, a packing of hemp, with white and red lead, and screwed up with 4 nuts and screws, or a washer of vulcanised rubber ⅜ in. thick, with screw bolts, is best. If the suction pipe is of gas-tube, the sockets must all be taken off, and a paint of boiled oil and red-lead be put on the screwed end, then a string of raw hemp bound round and well screwed up with the gas tongs, making a sure joint for cold water, steam, or gas.

Many plumbers prefer lead pipe, so that they can make the usual plumbers’ joint. The tail _m_ of the pump is for fixing the suction pipe on a plank level with the ground. Stages _n_ are fixed at every 12 ft. in a well; the suction pipe is fixed to these by a strap staple, or the action of the pump would damage the joints. There are two plans for fixing the suction pipe; (1) in a well _o_ directly under the pump; (2) the suction pipe _p_ may be laid in a horizontal direction, and about 18 in. deep under the ground (to keep the water from freezing in winter) for almost any distance to a pond, the only consideration being the extra labour of exhausting so much air. In the end of such suction pipe _p_ it is usual to fix an extra valve, called a “tail” valve, to prevent the water from running out of the pipe when not in use. The action is simply explained. First raise the handle _e_, which lowers the piston _b_ to _i_; during this movement the air that was in the barrel _a_ is forced through the valve in the piston _b_; when the handle is lowered, and the piston begins to rise, this valve closes and pumps out the air; in the meantime the air expands in the suction pipe _k_, and rises into the barrel _b_ through the valve _i_; at the second stroke of the piston this valve closes and prevents the air getting back to the suction pipe, which is pumped out as before. After a few strokes of the pump handle, the air in the suction pipe is nearly drawn out, creating what is called a vacuum, and then as the water is pressed by the outward air equal to 15 lb. on the sq. in., the water rises into the barrel as fast as the piston rises: also the water will remain in the suction pipe as long as the piston and valves are in proper working order.

The following table of dimensions for hand-worked simple lift-pumps will be found useful:--

+-----------+-------------+---------------+--------+------------+ |Height for | |Water delivered|Diam. of|Thickness of| |Water to be| Diam. of | per Hour at |Suction | Well Rods | | raised. |Pump Barrel. |30 Strokes per | Pipe. | for Deep | | | | Min. | | Wells. | +-----------+-------------+---------------+--------+------------+ | ft. | in. | gal. | in. | in. | | 14 | 6 | 1640 | 4 | 1 | | 20 | 5 | 1110 | 3 | 1 | | 30 | 4 | 732 | 2½ | ⅞ | | 40 | 3½ | 555 | 2½ | ¾ | | 50 | 3 | 412 | 2 | ¾ | | 75 | 2½ | 260 | 2 | ⅝ | | 100 | 2 | 183 | 1½ | ⅝ | +-----------+-------------+---------------+--------+------------+