Fig. 14.—Letting in fresh air.Fig. 14.—Letting in fresh air.
One of the simplest and best methods of providing an inlet for fresh air, without at the same time allowing blasts of wind to enter the room, is to fasten in front of the lower part of the window a board which shall just fill the window opening; then, raising the lower sash a few inches will allow fresh air to enter both at the bottom, where the board is placed, and at the middle of the window between the sashes (see Fig. 14). Persons sitting close by a window thus arranged may feel a draft even under these conditions, since the cold air thus admitted will sink at once to the floor and then gradually rise through the room to the ceiling, but unless one sits too near the window, this is an admirable method of admitting fresh air.
Another method, where steam or hot-water radiators are placed in the room, is to connect the outer air, either through the lower part of the window or through the wall of the room just below the window opening, with a space back of the radiator, so that the cold air entering will pass around and through the radiator and so be warmed as it enters.
Fig. 15.—Ventilating device.Fig. 15.—Ventilating device.
The picture (Fig. 15, after Jacobs) shows the arrangement of the radiators in one of the buildings of the University of Pennsylvania. A is the opening in the wallbelow the window;Dis a valve which regulates the amount of air entering through the opening;Ris the radiator;Bis a tin-lined box which surrounds the radiator;Tis a door in front of the box, which when raised allows the air of the room to be heated and to circulate through the radiator. By adjusting the two valvesDandT, air of any desired temperature can usually be obtained. Figure 16 (after Billings) shows an English device intended for the same purpose. The valveDin this case operates to admit air, either through the radiator or to the space between the radiator and the wall, in order to vary the temperature of the entering air. The valveTmay be open or closed, and its position, together with that of the valveF, determines the proportion of the room air which is reheated.
Fig. 16.—Ventilating device.Fig. 16.—Ventilating device.
The writer remembers one schoolhouse where these methods were used successfully, the radiators being placed directly in front of the window and inclosed at the back, sides, and top, except for an opening to the outer air through the wall, properly controlled by a damper. In the writer's own office the radiators are by the side of the window and are boxed in, the connection being made with the outside air through a wooden box entering under the radiator. This is an admirable method, provided the radiator has sufficient surface to warm the fresh air admitted.
Another excellent arrangement is to provide a narrowscreen similar to that used for protection against flies, but with the screening material of muslin cloth instead of wire cloth. This muslin will break up the current of air so completely that no draft is felt by persons sitting even close to the open window.
Position of inlet.
The inlet for fresh air, if connecting directly with the outside air, should not be at the top of the room, since then the inlet would not serve to admit air, but rather to allow the warm air of the room to escape, and a burning match would inevitably show a draft outward instead of inward.
Neither is it desirable to have the fresh-air inlet near the floor of the room unless the entering air is warm, because cold air admitted will flow across the floor and remain there, not disturbing the warm upper layers. The effect then is not to improve the ventilation, but only to chill the feet of persons sitting in the room. The position of the window lends itself, therefore, to admission of fresh air, since it is neither at the top nor at the bottom of the room, but at the level most suitable for such admission.
Foul-air outlet.
Very few houses have any provision for the outlet of spent air, and if ventilation is thought of at all, the only idea usually is to provide, in part at least, for the admission of air and to make no adequate arrangement for its egress. Whenever a stove or fire-place is in use, the mere burning of fuel requires the consumption of air, and in cases where apparently no air is admitted to the room, insensible ventilation is at work bringing into the room, through the walls and through cracks around the doors and windows, the necessary air for combustion.
Fig. 17.—Ventilation by means of coal stove.Fig. 17.—Ventilation by means of coal stove.
It may be proved by the laws of physics that a coal stove burning freely in a room causes adequate ventilation; and that only where the dampers of the stove are closed, so that not merely is the supply of fresh air diminished, but also the products of combustion are thrown out into the room, is there danger from lack of ventilation. The stovepipe in this case furnishes the necessary outlet for the impure air, and the following suggestion has been made in order to utilize this outlet, even when the fire is not burning freely or when the damper in the stovepipe is closed. If the stovepipe from a stove is carried horizontally, as it usually is, an elbow must be provided to raise the pipe to the stove hole in the chimney. Then providing a T connection at the point markedAin Fig. 17 (after Billings), the lower part of theTmay be carried to within a foot of the floor with a damper at the pointsBandC.When the fire is burning freely, the damper atCis closed, and ventilation is secured through the stove, the damper atBbeing open. When the damper atBis closed and the fire checked, then the damper atCmay be opened and the impure air drawn up the chimney from the level of the floor. This, it is said, is an effective arrangement for drawing off the polluted air of a room.
Fig. 18.—Coal-stove ventilation.Fig. 18.—Coal-stove ventilation.
Another method is to surround the stove with a sheet-iron casing, as shown in Fig. 18 (after Billings), the top of the casing having a pipe leading into the chimney independently from the stovepipe. The casing becomes warm and heats the room by radiation, just as the stove does, but if the damper in the flue from the casing be opened partly, a strong draft along the floor and into this casing will be developed and the foul air thereby discharged into the chimney. It will be easilypossible, of course, to carry away all the heat from the stove in this method, and the damper in the flue of the casing must be carefully regulated to carry away only the desired amount of foul air.
Fig. 19.—Coal-stove ventilation.Fig. 19.—Coal-stove ventilation.
Still another method of using the heat of a stove to secure ventilation is shown in Fig. 19 (after Billings). Here the stove is surrounded with a sheet-iron jacket extending from the floor to about six feet above that level. A pipe is carried from the outside air up through the floor directly under the stove. By regulating the damper in this pipe the supply of fresh warmed air entering the room can be regulated. Doors in the casing must, of course, be provided for the purpose of taking care of the fire,and of allowing air from the room near the floor to be heated instead of the outside air.
A most objectionable method of providing an outlet for polluted air from a room is to have a register in the ceiling with the ostensible purpose of warming the room above. It was the writer's misfortune once to stay a week in the country, in a room over the kitchen where this method of heating was employed, and the odors of cabbage, onions, and codfish which permeated the upper room, and clung there all night, still remain as a most unpleasant memory.
Size of openings for fresh air.
As an indication of the size of the openings needed, it has been said that in order to provide the necessary air movement, and yet to restrict the velocity of the moving air so that no objectionable drafts will be experienced, at least twenty-four square inches sectional area should be allowed as an inlet for each person, so that one square foot is required for six persons. This is, perhaps, a theoretical requirement. Certainly, it is more area than is likely to be obtained in actual ventilation. The space between two windows, for instance, is about one inch by thirty inches,—barely enough, according to this rule, for one person, and yet that opening is sufficient to appreciably improve the quality of the air in a room occupied by three or four persons.
Taking into account the necessary air required by lamps or gas burners, the inlet flue should have at least ten square inches area for each person, so that the ordinary single register should provide the necessary amount of air for a living room. When, as happens in houses where a studiedeffort is made to preserve the health of the inhabitants, an outlet is cut into the wall and a flue carried up through the roof, the flue should be preferably near the floor and on the side of the room opposite the window or inlet. With such an arrangement (see Fig. 20) the air entering rises at first, but sinks at once because of the temperature, so that the direction of the air currents are diagonally across the room from the ceiling to the floor, thus renewing and changing all the air particles except those directly over the outlet. Where the air is introduced mechanically, that is, forced into the room, it is better to have the inlet and outlet on the same side, so that the entering air is shot in at the top, flowing across the room, then sinking and coming back, just below the point where it entered.
Fig. 20.—Outlets into the walls.Fig. 20.—Outlets into the walls.
Ventilation of stables.
All that has been said on the subject of ventilation in houses applies equally well to the ventilation of stables, and a little book by Professor King of the University of Wisconsin, entitled "Ventilation," deals most thoroughly with the principles and practices of ventilation, not merely for dwellings but also for stables. Professor King proves by his experiments that the condition of cattle is much improved and that the milk-giving qualities are increased by a proper supply of fresh air, and in the book referred to, he gives a number of examples of the proper construction to provide adequate ventilation. It is most convincingto see how unscientific is the old-fashioned underground stable, the sole idea of which was to conserve the animal heat by crowding together the cows and by absolutely excluding the outside air. For further details of his work, its principles and practices, the reader is referred to the book, which may be obtained from the author at Madison, Wisconsin.
Cost of ventilation.
To ventilate a house is expensive, and to ventilate a barn requires not only a certain expenditure of money but also a considerable amount of judgment. It is evidently cheaper to heat the same air in a room over and over than to be continually admitting cold fresh air, which will have to be warmed. This extra cost is, however, not excessive, when the movement of the air currents is properly controlled. The cost of warming the air necessary for ventilation for five persons should not be, at the rate of 1000 cubic feet of air to each person, more than ten cents a day in zero weather, with coal at five dollars a ton. Enough coal will have to be burned in addition to compensate for radiation, or, in other words, it requires a certain amount of coal to keep an empty room warm in winter without any question of ventilation, and in some badly built houses this amount is large.
Relation of heating to ventilation.
It does not follow because much heat is lost in this way that the ventilation is good, since the heated air may ascend to the ceiling and there escape without influencing the ventilation. In fact, one of the first principles of ventilation is that as soon as regular inlets and outlets are provided, all other openings ought to be rigidly closed. Then and thenonly can the warmed pure air be admitted as desired, at the points intended, and the full value of the heat utilized. Especially is this control of openings important in ventilating barns. Here each animal is a natural heater, warming the air by direct contact and by rapidly breathing in and out large volumes of air which are thereby changed to a temperature of over ninety degrees Fahrenheit. The air around their bodies being warmed rises to the ceiling and spreads out to the two sides and is there gradually cooled and at the same time mixed with fresh air which enters at the top, so that the cow is constantly supplied with freshened air. A flue is needed to carry the foul air up through the roof, and fresh-air inlets in the outer walls on both sides are required, and with these openings carefully controlled and with no others interfering, the stable may be well ventilated, as shown in Fig. 21 (after King).
Fig. 21.—Cow-barn ventilation.Fig. 21.—Cow-barn ventilation.
In all cases where ventilation is to be practiced, the walls and ceiling should not merely be tight in themselves, but they should be double, and the strictest attention paid to limiting the amount of heat lost by radiation. All the heat used ought to be concerned in ventilation, and in that only. To secure air-tight walls and ceiling, the studding and joists should be boarded in, both on the inside and out, and the space between should be filled with shavings, straw, dry moss, or any similar fibrous substance. The outside sheathing must be well laid and must be water-tight in order that rain shall not penetrate to the inside of the wall, and the roof must be tight so that the ceiling filling does not get wet and rot.
The choice, therefore, so far as ventilation of either house or barn goes, lies between a poorly built, loose-jointed structure without artificial ventilation and with poor economy in heat, and a well-built, air-tight structure, with ample ventilating pipes, carefully and intelligently planned and built. The first is healthy so far as pure air is concerned, but drafty and uncomfortable. The second is more expensive to build, but insures lasting health and comfort. Then the choice cannot but fall on the building which is easy to warm, healthful to live in, and readily ventilated.
QUANTITY OF WATER REQUIRED FOR DOMESTIC USE
Until the last few years it has been a sad commentary on the intelligence of the average farmer that but few attempts have been made to supply the farmhouse with running water, adequate to the needs of domestic use. The men of the farm long ago realized that carrying water for stock in pails was both laborious and time-consuming, and very few barnyards have not had running water leading into a trough to supply the needs of cattle. In many cases this supply has been extended into the barn, and in some cases into individual stalls, so that the farmer has long since eliminated the necessity of hauling water for his stock. Perhaps, because the farmer did not himself carry the water, but rather his wife, he has until recently not concerned himself with any extension of the water-supply into the house, and so long as the well in the yard did not run dry, he felt that his duty had been done. To be sure, bringing water from the well to the house in mid-winter involves much exposure and sometimes real suffering; occasionally the farmer has been moved on this account to have the well located in the woodshed or onthe back stoop, avoiding the long outdoor trip, but increasing the dangers of pollution to the water. It would be interesting to make a census of the farm water-supplies in any county for the purpose of estimating the intelligence of the farm-owners, since one cannot but feel that such a primitive water-supply argues, in most cases, an undeveloped or one-sided intelligence on the part of the property owner.
Modern tendencies.
Happily, such primitive methods of bringing water to the house are being superseded by satisfactory installations, and one by one, each farmhouse is being provided with running water in the kitchen sink and with a bath-room containing all the modern conveniences. One cannot deny that this costs money, both because of the pipe line necessary to bring the water to the house and because of the plumbing fixtures required in the house. Again, a water-supply in the house involves a well-heated house, since pipes not kept warm will, in the winter, inevitably freeze, ruining the pipe line and perhaps the ceilings and walls of the house itself. But if the owner of a house has any money to expend in improvements, surely no better way of adding to the comfort and health of his family can be found. An abundant supply of water increases the self-respect of the whole family and has been known even to change the temper of an entire household. For another reason, also, it is a good investment, inasmuch as the quality of the water supplied from a spring on a hillside is, generally speaking, better than that of a well surrounded by barnyards and privies.
It has been said that the civilization of a community ismeasured by the amount of soap that it consumes, and it is almost the same thing to say that the refinement of a household is measured by the amount of water it uses. The poorer a family, the greater struggle it is to keep up the appearance of cleanliness, and no surer sign of rapid progress on a downhill road can be found than neglect of those practices which tend toward personal neatness. As the life of the farmer, then, becomes easier, as his condition becomes more prosperous, and as his family make more requirements, so, inevitably, is there in the farmhouse a greater demand for water in the kitchen, in the laundry, and in the bath-room.
Quantity of water needed per person.
Just how much water is needed in any house is not easy to predict, unless, at the same time, it is known, not merely the present habits of the family, but also their capacity to respond to the refining influence of unlimited water.
It has been shown by measuring the amount of water used in families of different social standing in cities of New England that the amount of water varies directly with the habits and social usages of the family. For example, in Newton, Massachusetts, where there are a large number of small houses with the water-supply limited to a single faucet, it was found that the water used amounted to seven gallons per day for each person in the house, while in houses supplied with all modern conveniences, the consumption of water was at the rate of twenty-seven gallons per day for each person. In Fall River, the conditions were much the same except that the poorer houses generally had one bath-tub and one water-closet, the amount of water used being eight and a half gallonsper head per day, while the most expensive house in the city used twenty-six gallons per head per day. In Boston, the poorest class apartment houses used water at the rate of seventeen gallons per head per day, the moderate class apartment houses at the rate of thirty-two gallons, first-class apartment houses at the rate of forty-six gallons, and the highest class apartment houses at the rate of fifty-nine gallons per head per day. The difference in these rates is easily understood by considering the habits of the individuals who make up the different classes referred to. In the poorer class of houses, the workers of the family are gone all day, and are too tired when home to spend much time in bathing. The children of such households are washed only occasionally, and the external use of water is generally regarded as an unnecessary trouble. In those families, on the other hand, where the necessity for daily toil is not so pressing, where bathing is more frequent, and where ablutions during the day are more often repeated, the amount of water used is much larger.
Another factor that affects the measured amount of water used in a family is the number of plumbing fixtures. At first sight, it would not seem possible that because there were two wash-basins in a house, an individual should use more water than if there were only one basin. Nor would it seem possible that an individual would take more baths with three bath-rooms available than if only one existed, and yet the number of fixtures does influence the individual who washes his hands frequently. With a wash-basin on the same floor, for instance, he washes often, whereas if it were always necessary to go upstairs for the purpose, his hands would go unwashed. Also, the morefixtures there are, the greater is the amount of leakage, since every faucet will, in the course of time, begin to leak unless the packing is continually replaced. The amount of leakage is, therefore, in direct proportion to the number of fixtures.
The amount of water used then, per head per day, varies from seven to sixty gallons, but only by an intimate knowledge of the habits of the household can one predict the amount of water likely to be used. Perhaps as an average in a house having a kitchen sink and a bath-room containing a wash-basin, bath-tub, and water-closet, a fair estimate of the water used would be twenty-five gallons per head per day. This amount must be multiplied by a maximum number of persons to be in the house at any time, and then this number must be increased by the amount of water used in the barn and in the yard, if these are to be supplied from the same source as the house.
Quantity used in stables.
The amount of water used in the barn is even more than that used in the house, a variant depending on the habits of the manager. The minimum quantity needed per day is determined by the number of pailfuls of water which each head actually drinks multiplied by the number of head. But besides this there are many other uses to which water may reasonably be put in connection with stock.
On a dairy farm, there is the water needed to wash cans and bottles and in some cases to furnish a running stream of cold water for the aerator. In some stables a large amount of water is used for washing harnesses and carriages; in others, but a small amount goes for such purposes.Some farmers have concrete floors in cow stables and pig pens and use a hose frequently to wash these floors clean. Other stables never see a stream of water and only see a shovel at infrequent intervals. The amount of water used outside the house is too uncertain a quantity to estimate on the average, but its influence and importance must not be overlooked.
Maximum rate of water-use.
It should now be noted that the quantity of water already referred to is the average quantity used through the twenty-four hours and does not mean the rate at which the water comes from the faucet. For example, three persons in a house use water, according to the above statement, at the rate of seventy-five gallons per day, but a whole day has 1440 minutes, and if seventy-five gallons be divided equally among the number of minutes, it means one gallon in every twenty minutes, or one quart in five minutes. It is obvious that no water-supply system for a house, designed to supply water at the average rate for the twenty-four hours would be satisfactory, since no person would care to wait all day for the amount. To wait five minutes to draw a quart of water would try the patience of any one, and while the total amount of water used in the house will be seventy-five gallons, provision must be made by which it can be drawn in small amounts at much higher rates. Practically all of the amount is used in the daylight hours or in twelve hours out of the twenty-four, so that the rate would be twice the average rate, and with this correction, two quarts of water could be drawn in five minutes.
But even this is too slow, and if one were to take a quartcup to a kitchen faucet and note the time necessary to fill the measure with the water running at a satisfactory rate, he would find that unless the cup was filled in about ten seconds it would be considered too slow a flow. Since it is possible for more than one fixture to be in use at the same time, the pipes ought to be able to deliver the total amount running from different faucets open at the same time, and if it is considered possible for three faucets to run at once, as, for instance, the kitchen faucet, bath-room faucet, and barn faucet, then the supply pipe must be able to deliver, under our assumption, three quarts in ten seconds, or at the rate of about six thousand gallons a day. It is necessary, therefore, to distinguish carefully between the total quantity of water used per day and the rate at which such water is used.
The first of these requirements governs the size of the reservoir from which the water comes or the yield of the well or spring, or the capacity of a pump from a pond to a distributing tank; the other requirement governs the size of the pipe or faucet or the capacity of a pump which supplies direct pressure. It should be noted also that with ordinary fixtures, the rate of delivery and the corresponding sizes of the fixtures are not affected by the number of persons in the house, whereas the first requirement, that is, the total quantity of water used per day, is directly affected by the number of persons.
Variation in maximum rates of water-use.
The quantity of water used, however, is not uniform throughout the day or the week. It is commonly known, for instance, that on Monday, or wash-day, when the well is the only supply, a great deal more water has to be carriedon that day than on any other day in the week, and this same increased demand for water is made when the water comes in pipes into the house. Probably about half as much water again is used on Monday as on other days.
Again, in the hot weather of summer, more water is used for bathing and laundry purposes than in cold weather. But, on the other hand, there is a great tendency in cold weather to let the water run in a slow stream from faucets in order to prevent freezing. This has been found to just about double the amount of water used. It is only a reasonable safeguard, therefore, if it has been decided that the family needs are such as to require twenty-five gallons per head per day, to provide for double that amount in order to meet the demands of excessive daily consumption or of the hot and cold weather extremes.
Fire streams.
If a water-supply is to be installed for any house, the possibility of providing mains of sufficient size for adequate fire protection should always be considered, although it may not be found to be a necessary expenditure. In case of a fire a large amount of water is needed for a few hours, entirely negligible if it is computed as an average for the year, but a controlling factor in determining the size of mains or the amount of storage.
A good-sized fire stream delivers about 150 gallons per minute, and for a house in flames, four streams are none too many. The rate of delivery, therefore, for a fire should be at least 600 gallons per minute or a rate of nearly a million gallons per day, and if it is assumed that the fire might burn an hour before beingextinguished, 36,000 gallons of water would be used. If a spring or tank is the source of supply, the storage should be 36,000 gallons, and the pipe line from the tank to the hydrants must be large enough to freely deliver water at the rate of 600 gallons per minute. If the distance is not over 500 feet, a four-inch pipe is sufficiently large; but if the distance involved (from the reservoir or tank to the farthest hydrant) is more than about 500 feet, four-inch pipe is not large enough. This is because the friction in a large line of pipe is so great that the water cannot get through in the desired quantity. A four-inch pipe, discharging 600 gallons a minute, would need a fall of one foot in every four feet, while a six-inch pipe would need a fall of only one in thirty. Of course, if the reservoir from which the water comes is at such an elevation that the greater fall is obtainable, the smaller pipe may be used. It is more than likely, though, that the reservoir is about 3000 feet or more away, and the entire fall available only about thirty feet or one foot in one hundred. Then an eight-inch pipe would have to be used.
Whether fire-protection piping, therefore, is a wise investment or not, depends largely on the cost of installation. A four-inch cast-iron pipe laid will cost about forty cents per running foot, while an inch pipe, large enough for everything except fires, will cost about ten cents, so that the excess cost per foot for the sake of fire protection is thirty cents, for a distance up to 500 feet (when the grade is 1 to 4) or $150. If the grade is not 1 to 4, then the pipe must be six-inch, and the excess cost is fifty cents or the cost for 500 feet will be $250. If the distance is greater than 500 and the fall not great, so thatan eight-inch pipe has to be used, the excess cost is sixty-five cents a foot, or $650 for a 1000-foot line.
It is sometimes possible to economize by building a large tank containing about 36,000 gallons and using only a small pipe to fill, but always keeping the tank full. Such a tank would contain 4800 cubic feet or would be twenty-two feet square and ten feet deep, or it may be twenty-five feet in diameter and ten feet deep. This tank would have to be erected in the air, higher up than the top of the buildings, and would require heavy supports and a great expenditure. Unless, therefore, a convenient knoll or sidehill is available on which to build a concrete tank, the large pipe direct from the water-supply must be provided for fire protection. Whether it is worth while depends on the cost of insurance and whether it is considered cheaper to pay high rates for insurance or to spend the large sum for protection. A third choice is also open, namely, to carry no insurance and to install no fire hydrants and to run the inevitable risk of losing the house by fire. Perhaps the decision is a mark of the type of man whose property is concerned.
Rain water-supply.
It will often happen that no pond or brook is available for a water-supply, and if water is obtained, it must come directly from the rain. Apparently, this is quite feasible, since an ordinary house has about 1000 square feet area on which rain water might be caught and carried to a tank. In the eastern part of the United States, the annual rainfall is, on the average, 3-3/4 vertical inches per month, or the volume of water from the roof will be 310 cubic feet. This is nearly 80 gallons a day, or enough for three or fourpeople. The rain from the house and barns might be combined, making perhaps 5000 square feet, and giving an ample volume of water for the needs of a dozen people.
In discussing the size of tank necessary to hold rain water for a family supply, it must be remembered that for many weeks at a time no rain occurs, and that a tank must be large enough to tide over these intervals of no rainfall. In the temperate zone there is no regularity in the monthly rates of rainfall. In the eastern part of the United States, the months of June and September are usually the months of least precipitation, although the general impression, perhaps, is that July and August have less rainfall than any other months. The truth is that, while wells and rivers are low in July and August, the actual rainfall for those months is not below the normal, and the low flows in the streams are caused by excessive evaporation and by the demands of growing crops. Although June and September have usually less rainfall than other months, in Boston the fall has been as high as 8.01 inches in June and 11.95 inches in September. Again, in Boston, typifying the eastern part of the United States, and taken because of the great length of rainfall statistics available there, the two months of highest rainfall on the average are March and August, and yet, in each month, in some particular year, the rainfall has been the lowest for any of the twelve months in the year.
As shown by statistics, the average rainfall in each month, taking a period of forty years or so, is practically constant for each month, and it is only the deviations from the average which would make trouble in a supply tank depending upon rainfall. Fortunately, statistics alsoshow that while a month whose average rate of rainfall is three inches may be as low as three tenths of an inch, it is not often that two months of minimum rainfall come together, and in looking over the rainfall statistics the writer finds that for any three consecutive months, including the minimum, the amount of rainfall is generally two thirds of the monthly average for that year; and this is stated in this way because it gives what seems to the writer a basis for determining a fair and reasonable capacity of a rain-water storage tank. It depends, one will notice, on the average annual rainfall; that is, on the depth to which the rainfall would reach in any year if none ran off. This varies from about ten inches in the southeastern part of the United States to one hundred inches in the extreme northwest, the average for the eastern part of the country being about forty-five inches, so that the monthly average is 3.75 inches.
Computation for rain-water storage.
With this for a basis, it may be determined how large a storage tank ought to be, assuming a family of five persons using water at the average rate of 25 gallons per head per day or 125 gallons each day. Doubling this amount to take care of emergencies and of the extra water used in hot weather, let us say that 250 gallons a day must be provided, or 7500 gallons a month. If we could be sure of starting at the beginning of any month with the tank full and that exactly thirty days would be the period of no rainfall, then a tank holding 7500 gallons would be the proper size. Unfortunately, with any month, as August, in which the rainfall may be practically zero, the preceding month may also have been so short of rain that the consumption wasequal to or even more than the rainfall, and the month of August would start with no rain in the tank.
But if we take a three-month period, those inequalities will be averaged and the supply will be, so far as one can foresee, ample in amount; that is, we shall take the supply required in three months, namely, 22,500 gallons, and subtract from it the amount of water furnished in the three months, which is presumably two thirds of the average rainfall on the area contributing to the tank. The normal rainfall in three months is three times 3-3/4 inches, or 11-1/4 vertical inches, and if this falls on a roof area of, say, 2000 square feet, the total amount of water is 1850 cubic feet or 13,875 gallons, and two thirds of this is 9250. The tank, then, must hold the difference between the 22,500 gallons and 9250, or 13,250 gallons, whereas a month's supply would be 7500 gallons. The actual tank, therefore, is made to hold a little less than two months' supply. Such a tank would be ten feet deep and fourteen feet square, a good deal larger tank, of course, than one ordinarily finds with a rain water-supply; but the estimate of the use of water has been high and a long period of rainfall has been assumed, so that there is little likelihood of a house with this provision being ever without water.
Computation for storage reservoir on a brook.
In determining the quantity of water that may be taken from a small stream the area of the watershed answers the same purpose as the area of the roof which delivers water into a tank, the only difference being that from the roof all the water is always delivered, except a small proportion that evaporates at the beginning of a rain in summer. From the surface of a watershed, on the contrary,a large amount, and in some cases all of a stream, will be absorbed by the ground and by the vegetation and will never be delivered into the stream which drains an area. On large streams it is fair to assume that, on the average, only one half of the rainfall on the area will reach the stream, while with sandy soils this may be as small as 20 per cent. From December to May inclusive, when the ground is frozen, when there is no vegetation to absorb the water, and when evaporation is very light, practically all of the rainfall reaches the streams. From June to August, on the other hand, when the soil becomes rapidly parched, when vegetation is most active, and when evaporation is high, frequently no rainfall reaches the streams and the ground water sinks lower and lower, so that often streams themselves dry up. It is necessary, therefore, in providing for a definite quantity of water to be taken from a reservoir built on a small stream, to make the reservoir large enough to furnish water from June to September without being supplied with rain. This does not call for a very large dam or a very large storage, and three months' supply will usually be ample.
We have already estimated above that the quantity of water needed for three months will be 45,000 gallons, or about 6000 cubic feet. If the reservoir is built in a small gulley or ravine, its width may be twenty-five feet. If the length of the reservoir or pond formed by the dam is 240 feet, then the reservoir will furnish 6000 cubic feet for every foot of depth, and a reservoir of that size holding one foot of water will tide over a dry season.
Evaporation during these same three months will use up about a foot and a half in depth over whatever area thereservoir covers, so that two and a half feet in depth must be provided above the lowest point to which it is desirable to draw off the water. It would be well to allow a depth of at least ten feet in order to avoid shallow, stagnant pools, and if this depth is provided, even more than the two-and-a-half foot depth mentioned might be withdrawn in extremely dry seasons, though perhaps at some reduction in the quality of the water.
Deficiency from well supplies.
A large number of water-supplies in the country, perhaps the largest number, at present comes from wells, either dug or drilled. It often happens that after plumbing fixtures have been installed with a pump to raise the water to the necessary elevated tank, the increased consumption causes the well to run dry for a number of weeks in the summer. The question then arises, Shall the well supply be supplemented or shall an entirely new supply be developed?
There are two methods of supplementing a dug well supply, and it may be of advantage to point them out. If the sand or gravel in which the water is carried is fine, it may be that the water will not at times of low water enter the well as fast as the pump takes it out. Such a well always has water in it in the morning, but a short pumping exhausts the supply. One remedy here is to provide a more easy path for the water, and that can be done by running out pipe drains in different directions. If there are any evidences that the underground water flows in any direction, then the drains should preferably run out at right angles to this direction, to intercept as much water as possible. The drains must be laid in trenches and besurrounded with gravel, and of course the method is inapplicable if the well is more than about fifteen feet deep, because of the depth of trench involved.
Fig. 22.—How a pump works.Fig. 22.—How a pump works.
Another remedy is to sink the well deeper, hoping to find a more porous stratum or to increase the head of water in the well. In one well, the writer remembers seeing two lengths of twenty-four-inch sewer pipe, that is, four feet, that had been sunk in the sandy bottom of the well by operating a posthole digger inside and standing on the top of the pipe to furnish the necessary weight for sinking.
Still another remedy is to drive pipe down in the bottom of the well, hoping to find artesian water which will rise into the well from some lower stratum. This method has been successfully employed in the village of Homer, New York, where the public supply formerly came from a dug well twenty feet in diameter. The supply becoming deficient, pipe wells were driven in the bottom and an excellent supply of water found fifty feet below the surface, the water rising up in the dug well to within eight feet of the surface of the ground.
If the well is a driven well and the water in the casing falls so low that the ordinary suction pump will no longerdraw, two remedies may be applied. A so-called deep-well pump may be used; that is, a pump which fits inside the piping and can be lowered down to the water level. The ability to bring up water then depends on the power to work the pump and on the presence of the water. Figure 22 shows the principle on which this pump works. At some point, it may be three or four hundred feet below the surface of the ground, a valveAopening upward is set in the well so that it is always submerged. Just above this is a second valve fastened to the lower end of the long pump rod which reaches up to the engine or windmill which operates the pump. At each up stroke water is lifted by the closed valveBand sucked through the open valveA. At each down stroke, the water is held by the closed valveAand forced up through the open valveB.
Fig. 23.—Pump installation.Fig. 23.—Pump installation.
The other method of developing a greater quantity ofwater from a deep well is to use air pressure to force the water either the entire distance to the tank or to a point where the suction of an ordinary pump can reach it, as indicated in Fig. 23. In this method an air blower is needed, and since this means an engine for operation, it is not generally feasible, but is suited to occasional needs, where an engine is already installed for other purposes and is therefore available.
The operation is very simple. An air pipe leads from a blower and delivers compressed air at the end of the air pipe, which must be below the level of the water in the well. The pressure of the air then causes the water to rise, the distance depending on the pressure at which the air is delivered.
Having arrived at the quantity of water necessary to supply the needs of the average household, we must next investigate the possible sources from which this quantity can be obtained. Before the advantages of running water in the house are understood, a well is the normal and usual method of securing water, although in a few cases progressive farmers have made use of spring water from the hillsides. It is rare, indeed, for surface water, so called, to be used for purposes of water-supply until after modern plumbing conveniences have been installed. Then the use of surface water becomes almost a necessity because of the large volume of water needed. The only drawback to its use is its questionable quality. Without modern plumbing, a well meets the requirements of family life, but does not answer the demands of convenience. With modern plumbing, a well is found to be pumped dry long before the domestic demands are satisfied. The result is an attempt to secure an unfailing supply, and for this a surface supply is sought.
Let us divide, then, the possible sources of water for domestic consumption into two groups, those found underthe surface of the soil and those found on or above the surface. In the first group will come wells and springs, and in the second group will come brooks, streams, and lakes.
Underground waters.
Springs result from a bursting out of underground waters from the confined space in which they have been stored or through which they have been running. Thus in Fig. 24 is seen how water falling on the pervious areaa-bis received into the soil and gradually finds its way downward between impervious strata which may be clay or dense rock. At the pointB, where the cover layer has, for any reason, been weakened, the pressure of the water forces its way upward and a spring is developed at the pointC. Or, conditions may be as shown in Fig. 25, where the confined water, instead of being forced upward by pressure, flows slowly out from the side of a hill, making a spring at the pointD, while the water enters the pervious stratum at the pointa-bas before.