"MILITARY. WATER SUPPLY - The problem of military water supply bears the same relation to similar work in civil life that military bridges do to those of ordinary construction; that is to say, although the ultimate object, and the underlying principles, are the same, the circumstances of construction are so different that the whole subject requires separate consideration. It has been long recognized that military bridges form a distinct branch of the art of war. Experience now points to the fact that water supply must be similarly treated. Of its great importance there is no question. The whole of the military operations in a campaign may turn on its adequate provision. The health and comfort of the troops and animals depend on this more than on any other supply question. Railways demand its provision, both in quantity and quality. It is therefore a matter both of operations and of administration, besides being an engineering problem of the utmost complexity.
In the following account of the most recent experience and practice connected with this subject, the purely engineering aspects of the problem will not be considered, and hydraulic calculations, sources of supply and the calculations entailed, well sinking and boring, pipe line design, reservoir dams and all other similar purely engineering technicalities will be omitted. It is proposed to consider the matter only in its military subdivisions.
I. Personnel. - The duties of officers and other ranks charged with water supply are broadly to carry out the engineering work involved in the obtaining and storage of water, and in the arrangements for insuring its purity till it reaches the custody of the troops supplied, and also to control all means of its distribution. There should be in all this organized work every care taken to ensure standardization of practice; there must be an adequate and competent executive staff, and efficient subordinates. On the staff of the engineer-in-chief of an army there should be an officer of high rank and of water experience, especially in charge of the whole control from the front to the base. There should be water engineers, under the chief engineers of the various formations, whose duties will be not only to carry out work actually ordered, but to reconnoitre, think out schemes, and generally to have such a grasp of the technicalities of the problem in relation to the whole military operations, that their advice may be of value to the army, corps and divisional commanders in considering the possibilities of operations. It is obviously of the very utmost importance that the general staff should keep the water engineers informed, to the fullest possible degree, as to impending developments, so that water policy may be framed accordingly.
As a general rule the field units of engineering carry out water supply as part of their normal duties, but in large operations they may be so fully occupied otherwise that it is necessary to provide special units for water duties. These would comprise (a) water supply companies, each about 8 officers and 250 other ranks, for general water work; (b ) lorry or barge purification units, each 5 officers and 120 other ranks, for operating purification plant; (c ) water control units, each t officer, 46 others, for provision of turn cocks, police at water points, etc.; (d ) water transport companies, 7 officers, 300 others for distribution by rail, road or canal, and (e ) well-boring sections, each 2 officers and 74 others for wells.
The equipment for these will vary according to the circumstances of the country. Obviously the water transport companies will have to be provided with many motor lorries fitted with tanks, and the purification companies with mobile laboratories. The above approximate sketch of the various units required will, however, indicate the nature of the equipment to be provided.
In any water supply scheme the aim should be to provide as much water as can be advantageously used, for abundant supply means health and comfort. But concurrently, there must be rigid control of distribution so as to ensure reduction of waste. In giving, therefore, certain approximate estimates of quantities required, it must be noted that, in hot climates especially, circumstances may call for considerable modification.
Men require, in semi-permanent camps with water-borne sewage, baths, etc., 30 gal. per head per diem; in standing camps, without water-borne sewage, 15 gal.; in temporary camps, 5 gallons. The absolute minimum is t gal. at rest, and on the march for periods not exceeding three days at a time z gallon. Horses in temperate climates drink 6 to to gal. a day and the absolute minimum is 3 gallons. A horse drinks 3 gal. at a watering, and takes 6 minutes to drink it. In hot countries and with much work horses may require more than to gallons. Oxen and mules drink as much as horses, sheep and pigs about I gal. per diem, camels to, with 20 every third day. A camel takes 20 minutes to water and drinks in two bouts with an interval of to minutes.
In hospitals and standing camps allow per diem, for each slipper bath 200 gal., W. C. 30, lavatory basin 20, urinal 40, yard tap 40, each vehicle washed to gallons.
On railways each broad-gauge locomotive needs 7,000 gal. per diem, each metre-gauge locomotive 2,500, 60-cm.-gauge 1,800. Horizontal stationary engines of compound modern type need 2 gal. per H.P. hour, and for the non-condensing type 4 gallons. For broad-gauge locomotives an alternative figure is 120 gal. per train mile. They require also for washing out about 3,000 gal. every 7 or 14 days. Boilers require about 20 gal. per H.P. hour under normal conditions. Petrol and oil engines require for cooling at rate of 7 gal. per H.P. hour and 35 gal. tank capacity per 6 H.P.
(a) When a forced landing is contemplated, arrangements must be made for seaborne water, in quantities much in excess of requirements, for accidents are almost certain to happen to some of the water-bearing vessels. Even if it is known that water does exist on shore, such precautions are necessary, for, in event of hostile resistance, it is more than likely that a retreating enemy will damage the existing supplies. Parties of engineers, provided with the proper plant and tools, must be told off beforehand for water-supply work on landing, and extra water carts, pack animals with filled receptacles, etc., should accompany the troops.
(b) When disembarkation takes place on friendly territory, watering arrangements - standpipes, fillers for water bottles, troughs for animals - must be provided near the points of concentration. The sites for such filling points must be carefully chosen so as not to impede concentration. Such work as this should be carried out by an advanced party of engineers, assisted by any local help available.
(c) For troops on the march, in a country reasonably well supplied, the procedure is for an engineer officer with a party of men equipped for testing the quality, and noting the quantities of water, to go ahead, fix watering places for men and animals, if possible improve the local conditions and generally make all arrangements so that everything may be ready in plenty of time before the troops arrive. But if the march is in a land that has no natural supplies or where the quality and quantity is doubtful, the problem is different. The first thing to establish is an initial watering point (I. W. P.) or points, as far forward as possible before the advance takes place. Water must be collected there in temporary tanks and so arranged that lorries can be filled quickly therefrom and dispatched regularly.
Adequate arrangements for the reception of the lorry-borne water must be provided at forward-water points, where the tank lorries can be quickly emptied into other improvised tanks whence they can be drawn by the troops in their water carts. At z gal. per man and 5 per horse per diem a division requires about 300 tons of water and this means 150 to 300 lorries according to the state of the roads, each lorry doing one trip per day. With pack animals, in countries where no roads are available, the same principles apply, only in addition to the contents of the receptacles carried for the troops, an allowance must be made for the carrying animals' own requirements.
(d) During position warfare there are three areas to be considered - forward, concentration, and back. The forward area, i.e. between front line and the rear of the heavy artillery zone, will require only drinking water for the fighting troops. This will be distributed (apart from any existing sources) usually from water carts or lorries filling at " ` points " in rear. Tank trucks on light railways and pipe lines to water points may possibly be used, but this is not so usual. While existing supplies should be utilized as much as possible, it is obvious that the greatest precautions against contamination are imperative. Distribution by water carts (holding 118 gal.) and water lorries, i.e. ordinary motor lorries fitted with two or more tanks, can be made where roads exist with sufficient security against hostile fire. They convey water from the supplies in rear to storage tanks of temporary construction. These "spill tanks" in the forward area should be small, numerous, and not too near each. other so as to -distribute risk of damage by hostile action. Sheltered positions, convenient for the troops, should be selected for their location. In some soils (e.g. in chalk) it is possible to mine underground tanks holding large quantities, and to bring supplies of water on light railway trucks. With heavy batteries in the vicinity of light railways such tank trucks can be used to deliver water to individual units. Storage for the daily supply must be arranged in such cases. A piped supply to a forward area is hardly practicable within 5,000 yd. of the line, where shelling is active. Such a system requires much care in maintenance, will be subject to great risk of damage and therefore to waste of water, hence it should not be adopted without full consideration of other alternatives. If adopted the general plan should be very simple, with as few branches as possible from main lines. It is better to construct radiating lines from the source rather than multiply branches. All pipes should be buried with 3 ft. of cover; although this involves their being out of sight, it is less disadvantageous than the exposure to shrapnel and frost. Protected shelters for pipe repairs and maintenance parties, together with supplies of tools and special fittings, must be arranged at intervals along the lines. As frequent breaks may be expected, frequent storage points must be provided; these will generally be a series of small tanks, say 400 gal. each, dug in and fed direct from the mains. Such points must be arranged to serve an area of the defence or made for the supply of dressing stations, etc. The ground must be well drained and all possible protection from shell fire must be given. The last stage of the travel of the water consumed by the troops in the front line must be by manual labour. Receptacles such as petrol tins may be used, and when filled may be carried to forward dumps on pack animals, tram lines, etc., so as to minimize hand carriage as much as possible, but in the last resort men have to be carriers. At the battle of Messines pipe lines were used to take water forward from catch pits on the Kemmel Hills, from sterilizing barges on the Lys, and from existing lakes, the quantity being 45,000 to 60,000 gal. daily. Arrangements were made to transport the water to the troops by pack animals and carrying parties. During the attack, water reached the troops within 20 to 40 minutes of the capture of positions. This is one instance out of many which illustrate the application of the principles above generally described.
It is in the concentration area (the line of demarcation between this and the forward area being taken as the rear of the heavy batteries) that the main source of supply and main arrangements for distribution to the forward area will be carried out. There will be in addition extensive arrangements for troops in reserve, casualty clearing stations, etc. Whether a comprehensive pipe system should be constructed, whether there should be a number of pumping stations, or whether there should be one or two main installations, are matters which will have to be carefully considered in the light of local circumstances and available labour and plant. In any case a thorough system of control with personnel trained in manipulating the various valves governing the branches, and a time-table giving equitable distribution, will have to be organized. The concentration area will be divided up into water areas with water "points" whence fighting units can draw their supplies by means of their water carts, but there will be casualty clearing stations requiring special attention where water should be laid on to standpipes near kitchens, ablution rooms, operating rooms, etc.
In the back areas the circumstances resemble those of a semipermanent camp. The requirements will be for divisions in billets, reinforcement camps, schools of instruction, etc., and the arrangements only differ from those in regular encampments in cases where in villages, etc., it is found more convenient to have water cart points rather than piped supplies laid on to camping grounds.
(e) Before and after an attack the water supply arrangements include the supply during concentration, and keeping up supply as the troops advance. In the former case the work is very much as xxxzl.-31 already described for position warfare. Every endeavour must be made to develop resources rapidly and secretly on all parts where attack is contemplated, and the most thorough training must be given to the technical troops in the rapid extension of the water system. In Palestine prior to the great attack, material was brought during night to the farthest advanced positions, and concealed in orange groves, etc., while the personnel was drilled in rapid laying of pipes and erecting of pumping plant. The supply after the initial advance will depend on the nature of the country and the initial success, and the most complete and accurate intelligence of the water resources of the country is of paramount importance. While the construction of pipe lines in the rear of an advancing army may be of the utmost value in securing a position won (as at the Somme in 1916), it is hopeless with a rapid advance (as in Palestine in 1918), so that in this case either independent sources of supply must be relied on, or transport by lorry must take place, and this places a tremendous strain on the transport organization and is, therefore, not lightly to be considered. Where pipe lines are decided upon, it is well to take them in entirely fresh installations rather than attempt to extend existing systems.
(f) A few details may be added of various constructional matters common to all phases of operations.
" Filling points " are tank and standpipe installations where water carts, lorries, " dixies " and water bottles are filled. Preferably there should be separate standpipes and approaches for carts and for lorries, so that the one may not impede the other, but all the standpipes should be such as can be equally used by either. There should be provision off the main road for waiting vehicles (within call of the " point " police).
As there is a limit to the number of horses that should be watered at one point, it is best to establish numerous small " watering points," with 200-ft. run of troughs as a maximum, and to locate the positions of the stables accordingly. The troughs should be near a road, but not next a main road where strings of horses would impede traffic, and, above all, horses must not cross a road to reach the troughs. The approaches to the troughs and the standings must be well made, drained and fenced in; otherwise the whole place becomes a morass. The frontage for each horse at the trough is about 21 feet. In an actual instance 6,000 cavalry horses per hour were watered at 500 ft. of trough, using both sides. This works out at 12 horses per ft. of double troughing, each horse being 5 minutes inside the enclosure. Probably the best figures for general use are 6 minutes each horse and 22 ft. frontage. If watering is to be on both sides the trough should be at least 3 ft. wide. Canvas troughs (boo gallons) are 36 ft. long, and should be in strong framing.
Where, as is often the case in Oriental countries, water lies deep below the ground, necessitating the use of pumping machinery, the watering of large numbers of animals becomes exceedingly difficult. In the Palestine campaign the water distribution unit was I lift and force pump, with hose, and i 600-gallon trough, which unit with good management could water some 180 horses or 54 camels per hour. Only 18 camels can use a trough at the same time, and each relay takes 20 minutes to water. The requirements of a division are about i oo,000 gallons a day, so each field company of Water Engineers carried 12 water units, or 36 per division. For the men's drinking water 10 large canvas tanks each holding about 1,500 gallons are needed. For storage, while at rest, large canvas bucksails, specially proofed and holding some 7,000 gallons, are useful, but it has been found better to construct tanks of masonry or planking and to reserve canvas tanks for mobile use. Copper vessels, holding 12 gallons, called fantassis, were used for camel transport.
Some notes may here be given about Oriental methods of raising water. The shadoof is a bucket hung by a rope to a horizontal swinging pole, slung from a vertical standard and weighted at the end furthest from the bucket. It can raise about 1,500 gallons an hour from a depth of 6 feet. The Persian wheel or sakkieh, a system of small jars working on an endless band round a vertical wheel above a well, and actuated by oxen or camels turning a horizontal wheel, - can raise 3,000 gallons an hour from 40 feet. The charsa, or skin bag, worked by a bullock hauling a rope attached to the bag over a pulley above the well, can raise 1,500 gallons from 40 feet.
This is a comparatively easy problem. Certain quantities of supply will have to be assumed, in accordance with experience in similar cases, at various points, and then the sizes of the pipes can be calculated by ordinary hydraulic rules. But it is well to keep the sizes of the pipes fairly uniform, giving rather larger than the calculated diameters, both because the data on which the calculations are based are at best conjectural, and because it is well to avoid a multiplicity of different sizes. In designing the system it should be arranged that " dead ends " of pipes are avoided, i.e. that the possibility of water remaining stagnant in an isolated length of pipe should be reduced to a minimum. Supply will be from an existing town main, or from some independent source (well, river, etc.) whence the water is pumped to an overhead service reservoir that overlooks and can supply by gravitation the whole system.
A safe water may be turbid in appearance and even disagreeable to taste and therefore repulsive; a dangerous water may be clear and palatable and therefore attractive. War experience has shown that few waters are so foul that they cannot be rendered safe by suitable treatment. The aim of purification is to obtain an effluent which is not only safe, but is palatable, of good appearance and attractive.
Water for horses is not usually purified. Almost any clear river or pond may be used in the crude state, and the instinct of the animals often leads them to refuse a contaminated water, even if it looks pure. In many cases in Flanders in the World War water from ponds and marshes, though foul and repulsive, was made quite potable by simple treatment. The military value of this fact is evident. Broadly speaking the purifying processes are those which remove suspended matter, and those which render innocuous bacteria which would be harmful.
English waterworks practice in civil life relies almost entirely on the action of the gelatinous film forming on the surface of a sand filter, for removing bacteria, but the processes of sedimentation, filtration and oxidation, which purify water in natural streams and lakes, can be imitated by artificial means working more rapidly than the ordinary sand filter process. Sedimentation can be accelerated by the addition to the water of an alum solution. Filtration can be effected by passing the water under some pressure through a porous medium; oxidation of bacteria by agents such as chlorine in measured quantities. In the field the steps taken are to precipitate the suspended matter by alum solution and then to treat the clear water by chlorination. The former process, though helpful in the latter treatment, is not in itself sufficient to produce a potable water. Chlorination is generally effected by introducing into the water a solution of calcium hypochlorite (bleaching powder) by means of the Horrocks apparatus. This is designed so that a test may be readily applied by men of intelligence to ascertain the condition of the water as regards free chlorine, and to calculate from this the amount of bleaching powder which must be introduced in order to destroy bacteria.
The apparatus for chlorination consists of a box containing six cups to be filled with the water, two tin spoons each holding 2 grammes of bleaching powder, a special cup for the chloride of lime solution, glass bottles containing a test solution of zinc iodide and starch (which has a certain colouring effect on water containing free chlorine), pipettes, stirring rods, etc. The method of using is to put varying quantities of the test solution in each of the six cups of water and observe after half an hour. From the coloration of the water, bleaching powder in proportionate quantities is added for every 100 gal. of water in the chlorinating tank.
Poisons can be removed from water by various chemical processes, though it may be easier and cheaper, and certainly safer, to transport other water by road or rail rather than trust to remedial measures. A contaminated well can be rendered usable in a few days by cleaning out and continuous pumping, and in the case of organic pollution by the addition of large quantities of bleaching powder, followed by pumping out after a period of rest.
VI. Plant and Machinery. - The British service water cart (Mark VII.) holds 118 gal. and consists of a galvanized iron cylinder, together with filtering apparatus, two pumps, a box for small stores, a sterilizing kettle, the whole being mounted on a wooden frame with cranked axle and, wheels for horse draught. The two filters are placed on the frame in front of the cylindrical tank and can be used either separately or together. Each consists of a steel cylinder in which is contained a cloth-covered steel reel and a chamber for the clarifying powder.
Tank lorries are ordinarily improvised from ordinary motor lorries by mounting two 30o-gal. tanks anchored to a wooden frame bolted to the chassis, with a 2-in. pipe connecting the tanks and a 2-in. draw-off. These tanks should have internal baffle plates to reduce the swaying action of the water in travelling. Another method is to sling canvas tanks from framing on the lorry.
The Norton tube well, a perforated tube with hard driving head, and driven by blows from a " monkey," is useful in obtaining supplies near the surface in certain soils. Used with a lift and force pump they are suitable for small installations, but they only yield 200 gal. per hour. They were very useful in the cavalry operations in the Sinai peninsula, where water was, by their use, frequently obtained in the dry beds of wadis. The lift and force pump, which is an article of store, can lift water through a suction hose from 20-28 ft. and force it to a height of 60 ft. above its former level. It consists of a horizontal barrel 42 in. bore with a double piston working with a 4-in. stroke and operated by a crank pivoted above the barrel and worked by manual power. The suction hose comprises four 12-ft. lengths of prepared hose, internally wired, and at the end there is a strainer, a perforated steel drum. The delivery hose consists of one 30-ft. length of 2-in. canvas hose. This pump is very handy and easily worked by unskilled labour.
Other pumps for manual power are the semi-rotary for small deliveries up to 30 gal. a minute (an ordinary piston and plunger pump) and the chain helice pump, which is an endless chain, or spirally wound band, with a weight at the end suspended and worked by a vertical wheel at the top of the well. The surface tension of small quantities of water adhering to the links of the chain, or the spiral band, is not broken in the rapid movement of the rising chain until it is discharged at the summit of the circuit. It is a very simple form of pump, but only suitable for small discharges.
Of the many patterns of power pumps there are comparatively few that meet the needs of an army in the field, in respect of being easily transported, reasonably free from chance of breakdown, and economy of fuel. It is important that the types used in the field should be few and that parts should be standardized so as to facilitate repairs. There should always be a number of spare parts accompanying each machine, and there should be other spares kept for general use at store depots. All suction and delivery connexions especially should be standardized. As a motive power, high-speed internal combustion engines are generally of most use, if properly connected with the pump and operated by competent personnel. Slow and medium-speed oil engines may be found very useful.
A pumping set will generally consist of (i.) prime mover, direct gear, or belt coupled to (ii.) pump with valves, strainer, suction piping and foot valves (iii.) starting gear for engine or motor, set of spanners, etc. Different classes of pumps will be required for delivery to tanks near the supply, hasty installations on pipe lines, deliberate installations for rest camps, etc., and pumping from deep wells. The variety of pumps suitable for each class is considerable. Mention, however, may suitably be made of the air lift pump, which, on account of its having no working parts below ground, and for several other reasons, is the most useful form of pump for military work. Such a pump can be mounted on a lorry and can go round a series of wells, pumping from each the day's supply into an extemporized reservoir and then going on to the next. It is a device for raising water by compressed air introduced in a vertical tube connected with the rising main, either concentrically with that pipe, or in a separate tube parallel to it. The utility and efficiency of this device has been amply tested in war, and much attention and valuable experience has been devoted to the theory and practice of its use.
As regards pipe-laying, cast iron pipes, though ordinarily used in civil water supplies, with their lead joints are unsuitable for military work because of the relatively heavy weight as compared with steel tubes of the same diameter; also they are brittle and unsuited for rough handling, and the jointing takes more time than the screwing up of steel tubes. The latter should, therefore, be invariably used in the field. As a rule they are not made of larger diameters than 6 in., but larger pipes can be obtained, and many miles of io-in. and 12-in. pipes were put down in the Sinai peninsula in 1916. For most purposes wrought iron screwed and socketed piping is suitable; the British standard threads for the pipe ends should be insisted on, and the whole should be capable of standing a test of 300 lb. per sq. in. (690-ft. head). If in mountainous country (as with the British in Italy, where heads of 2,000 and 4,000 ft. had to be negotiated), the pipes must be of the hydraulic type, with special joints.
Many special fittings are required with a pipe system, elbows, tees, crosses, etc., and many devices for control and delivery, such as valves, taps and stop cocks. The main point to remember is that there is no economy in having inferior and cheap fittings, for the waste of water which follows their use costs far more than the extra cost of water and more reliable articles. (G. K. S. M.)