ESTABLISHING A FARM WATER SUPPLY SYSTEM

New Zealand Journal of Agriculture, Volume 78, Issue 2, 15 February 1949, Page 179

ESTABLISHING A FARM WATER SUPPLY SYSTEM

IN the first section of this article which was published in last month’s “Journal,” H. W. T. Eggers, Engineer, Department of Agriculture, Wellington, discussed the selection of a source of water supply, different water supply systems, pressure, storage, and volume, and equipment used in water supply systems. This concluding section deals chiefly with the position of fittings, auxiliary equipment, the installation of a water supply system, and purification of water. IN planning the layout of a piped water supply the arrangement of equipment available on the market has to be considered and two principles must be observed: Utility and economy. Utility means a handy, trouble-free system that gives water in the quantity and at the points required year by year with no more attention than routine maintenance. Economy means a system installed at a minimum expense without sacrificing utility and one that will operate for a reasonable period without the recurrence of capital expenditure for replacement parts. The correct choice and positioning of piping and fittings, the correct choice and siting of pumps and reservoirs, and the correct choice of power will give both utility and economy. Attention should be given to the following points in deciding the physical layout of the system: — 1. The positioning of gravity storage in relation to the points of outlet should be arranged to give minimum length of pipe runs. 2. The positioning of a pump in relation to gravity storage should be arranged to give minimum length of pipelines, both suction and discharge, and minimum length of powerline if the pump is electrically operated. A , compromise may have to be made between length of pipe and

length of powerline, with concession in length to whichever is the less expensive to construct. 3. The positioning of a pump in relation to a stream should be such that minimum interference is caused byflooding, silting, or debris. Pump suction facilities should be arranged to avoid interference from these sources. 4. Taps or outlet valves of the Correct size to suit pressure and required volume should be placed in the most convenient positions. 5. The capacity of service mains supplying points of outlet should be capable of providing for any future loading as well as for immediate needs. Plugged T pieces should be provided on service mains where it is considered future connections may be required. 6. Sufficient control valves should be provided to enable sections of the system to be isolated for maintenance with, out interruption to the whole system; for example, where a ball-cock is installed a control valve should be provided. 7. Master valves should be provided at storage outlets to enable the complete system to be isolated. 8. Where pumping to a high head or to the bottom of a reservoir a check valve should be installed between a stop valve and the pump to enable the pump to be opened up without loss of water in the delivery pipe. The provision of a stop valve is a precaution in case the check valve is damaged. Check valves should be used in all cases where uni-directional flow is desirable. 9. High points in pipelines where air can be trapped should be avoided, and if this is not possible, air valves must be provided; otherwise air locks will occur.

Methods of Economy

To economise in the use of pipe, branches from the service main to the taps or points of outlet should be as short and as direct as possible. Several outlet points maybe supplied by one pipe connected to the service main, provided its size is proportioned to the volume required for the number of points likely to be in use at any one time.

'■ A saving in piping can be made where a pump line runs parallel to a service main from the reservoir. Fig. 18 shows how one pipeline may be arranged at the reservoir to carry the intake from the pump and the outlet flow to the service main. If the pump main and service main differ in size, the larger must be used from the junction of the two to the storage reservoir. Auxiliary Equipment Tanks, dams, filters, stock-watering troughs, and water softeners form part of water supply schemes and can be considered as auxiliary to the main scheme of supply, storage, and distribution. Tanks Tanks may be built of a variety of materials, constructed to any suitable shape, and mounted either above or below ground to suit the layout of the water supply system. . Steel tanks: Most dwellings in which a rain-water supply is obtainable by roof catchment are provided with galvanised, sheet-steel tanks, the most common being the square 400-gallon and the round, corrugated 500-gallon tanks. The tank is always mounted above ground level, usually low enough to enable collection of roof water and high enough to provide some gravity fall to the taps. These tanks should never be installed singly, except where the loss of water from the tank would not matter. It is better to provide two smaller tanks with an isolating valve between them than one large one. This enables one tank to be emptied ahead of the other and permits the Eeriodical cleaning out of both tanks, •own-pipes, covers, and vents should be arranged and protected with wire gauze so That vermin or debris cannot gain entry. Down-pipes can be carried into a funnel with sufficient screen

area to allow the maximum volume of water to pass. Dwellings near the sea that depend on roof water should have detachable down-pipes to the tanks. During fine weather the pipes are removed from the tanks, and after rain has washed the roof for 15 minutes the pipes can be replaced and the water collected. This precaution is necessary where such water is used for engine-cooling, as spray-laden winds off the sea cause a deposit of chlorides on the roof, which is carried into the tank by rain and can cause rapid corrosion of engine-cooling water jackets. Cast-iron, segmental tanks: These tanks have the bottom and sides built up of cast-iron segments and are made either square or round. Such tanks are built for bigger capacities and are usually mounted on a steel structure at an elevation sufficient to provide gravity head.

Wooden tanks are made for airly large capacities and are usually built from wooden slats bound with steel bands in the same way as a barrel. Tanks of this type are used at railway watering places. Pre-cast or spun-concrete tanks: Reinforced pre-cast or spun-concrete tanks can be obtained in a range of capacities up to about 1000 gallons and are suitable for placing either above or below ground. They are watertight, and if properly installed, present no maintenance problems. Reinforced concrete tanks can be constructed to any shape and capacity for placing either above or below ground. Tney should be built by an expert, because if the shape of the tank is not properly designed and the size and positioning of the reinforcing steel are incorrect, the tank will not be successful. Underground or partially-under-ground concrete tanks are ideal for storage of rain-water in districts subject to long dry summers; if enoughstorage is available, winter rainfall in New Zealand is usually sufficient to provide water for a year-round supply. The method is to retain one or two 400-gallon tanks to provide a gravity head to the pipe system and run an overflow from these to underground storage. These tanks would always be full during the winter, and any surplus would overflow and be stored in the concrete tanks for use in summer. During summer, when rainfall is limited, water is pumped from the concrete tanks back to the gravity tanks as required. A . sectional view of a semi-under-ground, round, concrete tank is shown in Fig. 19. This type of tank is normally provided with a timber roof covered with tarred roofing material and supported on a central column. An underground, rectangular tank is built in the same way as a round tank and may be made with either a pre-cast slab top or integral reinforced top. Dams Dams are the retainers of reservoirs formed in creek-beds or river-beds, and may be required to provide feed and storage for a natural gravity system or to feed a drive pipe for a hydraulic ram. In either case the provision of a dam in a permanent water supply should not be contemplated without due consideration to its location, freedom from fouling, and protection from stock. If the water

supply is to be drawn from a stream that must be dammed to provide storage, the volume of flow should in all cases be greater than the draw-off, so that the dam will act more as a weir and the water in the reservoir behind it will be constantly changing, the excess flowing over the dam. Dams should be sited on streams above the point where stock have access to the stream and fenced off. If the dam is not surrounded by bush, trees should be planted round it to keep the water cool. Stock can be provided with a drinking place below the dam. As a foul dam can afford a likely source of stock infection by internal parasites, it should receive chemical treatment when necessary to clear it of sediment, organic matter, and algous growth. Expert advice should be obtained when this treatment has to be given. Log dam: Fig. 20 shows the construction of a log dam, which is formed by placing beech or other suitable logs horizontally across the stream. A trench about 3ft. long is cut into each bank down to the level of the centre of the streambed and the logs are dropped into it. Short, vertical, pointed poles or logs are driven down at each side of the stream to protect the banks and lessen the risk of their being scoured away in a flood. It is advisable to put in the side poles first, a gap of sufficient width being left for the horizontal timbers to be inserted afterward. The site chosen for the dam should be one where the banks are free from boulders or tree roots and where the bed at the base of the dam can be cleared of as much loose material as possible. If possible, it is advisable to get the bottom horizontal timber well below the natural bed of the stream. When all the timbers are in place they should be thoroughly backed with stiff clay puddle, which should be well rammed down behind the horizontal timbers and the side piles. The side piles should be high enough to reach a few inches above the top of the banks. The feed pipe from the dam is fixed with its top 12 to 15in. below the overflow level and its mouth should be protected with a rose or strainer of suitable dimensions. The same type of dam can be built with old, creosoted railway sleepers instead of logs. Standard sleepers may be used for the side piling, and if longer ones are needed for the horizontal timbers, “crossing sleepers” can be used. Bag dam: Fig. 21 shows the military method of building a dam by the use of bags of dry-cement concrete dropped into the stream one over the other till the water is raised to the required level. This is the simplest method of building a substantial and permanent dam. The streambed and side banks should first be cleaned and all loose boulders or roots taken out. The concrete should be in the approximate proportions of 1 part of cement: 2 of sand: 3 of gravel (5 : 1 mix by volume). The bags used should be only about two-thirds filled so that they will “bed” well one on the other to form a compact mass when set. The concrete must be thoroughly mixed (dry) before being put into the

bags, which are gently dropped into the water in rows, as shown in the diagram. The portion of the dam above water level may be built of concrete in the ordinary way, and the draw-off pipe should be inserted at the proper level. . Reinforced-concrete dam: A dam built of concrete reinforced with steel rods or bars is shown in Fig. 22. By the use of reinforcing that is correctly sized and properly spaced the concrete walls and buttresses may be of com-paratively-narrow dimensions, walls of Sin. thickness being sufficient for a fairly-large dam. To be effective reinforcing of concrete must be designed and not done haphazardly; reinforcing with scrap iron and old bedsteads is worse than useless. Solid-concrete dam: Fig. 23 shows a solid-concrete dam with the jambs of the crest grooved. By the use of planks in the grooves the level of the water can be regulated to some extent according to the volume of water flowing. The supply pipe is laid from a small intake well with an iron grating on one side of the dam. Filters Where tank . storage for a piped water system is liable to become contaminated with foreign material it is advisable to install a filter between the supply and the storage tank. Several types of pressure filters with a wide range of capacities are manufactured and can be installed on the supply line if the supply has a gravity head. They should preferably be installed in pairs and each fitted with isolating valves to allow one to be cleaned while the other is in use.

... The filtering medium of pressure filters may be processed chalk or charcoal, and sometimes sandstone is used, The chalk or charcoal may be arranged either as a candle or plate and the sandstone as a dome, and to facilitate cleaning, the outside of each type is exposed to the polluted water. These three types of pressure filters are shown in Fig. 24.

A simple type of filter adaptable to ball-cock control is the cascade filter, shown in Fig. 25. This is a gravel-bed type of filter built in reinforced concrete and it can be proportioned to suit the location and the requirements of the water supply. Pumice can be used for the bottom filter bed in place of coke or charcoal. It should be remembered that filters are not purifiers and will not separate dissolved mineral or chemical salts or , all bacteria from the water, but only solid or vegetable matter held in suspension. Water Softeners In most locations where the natural supply is hard the water is used for stock and a rain-water supply is arranged for the dwelling. This arrangement has drawbacks, as sufficient rain-water, storage is seldom provided to meet peak, requirements and the dwelling is without water in a dry summer unless a by-pass from the stock water supply has been provided. Immediately hard water is admitted to the domestic system the advantages of having an independent soft-water supply are lost. The provision of a water softener between the hard sup- • ply and domestic demand can eliminate this disadvantage and probably make the stock water supply permanently available for domestic use, allowing the rain-water supply to be dispensed with, though some rain-water storage should be retained as an emergency. To get an exact measure of the hardness of water a rather elaborate method is necessary. However, a fairly-accurate measure can be made by the so-called “soap test,” which is carried out as follows: Put 22 c c of the water to be tested in a small, clean, „glass bottle ■ of a capacity of about 80 c.c. or 3 fl. dz. Add “standard soap solution” to the water one drop at a time, shaking the bottle vigorously ter each drop. The number of drops that must be added to produce a substantial lather on the water after shaking is the approximate hardness, expressed m number of grains. Thus, if it requires 8 drops of soap solution to form a lather, the water tested has about 8 grains of hardness. Best results are obtained in this test if the soap solution is added with' a dropper.

Though standard soap solution may not be obtainable from chemist shops, it is available from wholesale drug merchants. • Hardness of water is usually expressed in parts per million, and as 17.1 parts per million are equal to one grain of hardness, water having 8 grains of hardness would have 8 x 17.1, or 136.8 parts, of lime or gypsum to each million parts of water. The commercial water softeners available for removing hardness consist of a tank of chemicals or minerals (zeolite) through which the water flows on its way to the domestic supply. The chemicals or minerals reduce the calcium content of the water, but as they eventually lose their potency, they require to be revived by washing with a brine solution. Most commercial water softeners are provided with equipment to enable this reviving to be done quickly and easily by using common rock or block salt. If the water contains a considerable quantity of iron, it should pass through an iron filter before the softener, as the iron may accumulate in the softener and destroy its effectiveness. Furthermore, the removal of the iron from the water will make the water clearer and will reduce the staining of plumbing fixtures and clothing washed in the water. Facilities for Using Water As - water is required on farms for domestic use, washing and sterilising in the milking shed, watering stock in paddocks, cultivation of crops in the garden and orchard, and for fire-fight-ing and general purposes around the homestead,' different facilities are necessary for convenience of applying water to its various uses. Domestic Use The domestic uses of water are for the washing of dishes, and clothes, for personal washing (and if drainage is fitted, toilet purposed, and for drinking and cooking. To provide for these purposes bathrooms, kitchen sinks, and wash-houses are provided with running water, and if these units are fully convenient, both hot and cold water is available. The placing of such units as bathroom, kitchen sink, and wash-house in a house depends on individual requirements and on the design, but both requirements and design are often decided without reference to water supply or drainage, and expense is incurred which could have been avoided if the plumbing layout had

received consideration. The plan which takes into consideration the plumbing layout need not detract from requirements and can be just as pleasing as any other, yet have a plumbing system less costly to install and probably more efficient. Points to remember in considering a plumbing system in relation to house design are: First, pipe runs, particularly for a hot-water system, should be as short as possible; and second, drains should contain as few bends as possible. These points have been observed in the English mass production of a central unit round which the house is designed. This unit can be placed at right-angles to an outside wall and contains bathroom facilities on one side and kitchen facilities on the other, with a solid-fuel fireplace for a sittingroom on the end opposite the outside wall. A hot-water cylinder heated either electrically, by gas, or from a wet-back in the solid-fuel fireplace is built into the unit. In this way internal runs of piping are reduced to a minimum and external mains for gas, water, sewerage, and electricity are brought to the one point outside the building. All designs might not lend themselves to the adoption of a unit of this type, but whatever the design of a dwelling, the points of usage of water —bathroom, kitchen, and wash-house —should be as close together as possible and preferably on only one side of the house so that drains can be laid in a straight run. This not only reduces plumbing costs, but tends to give a more efficient hot-water system, as less pipe radiation takes place. Before alteration or installation of a cold- or hot-water system is planned for a house an inspection should be made to see whether greater convenience can be obtained by changing the positions of such work places as the sink rather than by piping the water to the point where it was used hitherto. Running water may not save much time and labour if the working area is still inconvenient. The sink should be placed convenient to the light, be provided with ample bench space on either side, and be at correct height for the average worker. (The average height of 32in. for a sink bench is generally rather low, and 34in. may be found more convenient. A few inches more or less can mean the difference between comfort and discomfort in the routine task of washing dishes.) If the hot-water system is heated by electricity, a range, or a chip heater, a

great deal of heat will be saved if the piping is copper and well lagged. In a long hot-water run intermittently used a pipeful of hot water is left to cool by radiation every time water is drawn from the run. A short run well lagged means less heat loss. The use of copper not only minimises corrosion, but minimises heat loss, as copper is a quick conductor of heat, and if lagged, less heat is dissipated. Copper pipe is also thinner than steel, so there is less metal to absorb the heat. ' . - ■ If a piped water supply is to be altered or installed in a bathroom not arranged conveniently, opportunity should be taken of replanning the layout of the bathroom. A wash-basin may perhaps be moved to a position where a wall cupboard with a mirror inside the door can be provided, or if the bath is . an old-fashioned type, it can be boxed in to eliminate having to clean underneath .it. Thoughtful planning will soon reveal alterations that can be made to ease the routine work in the home; for example, the provision in, say, the back porch of a wash-basin fitted with hot- and coldwater supply would avoid the need for people who have been working outside to walk through the house to wash at mealtimes, . thereby helping to keep both house and bathroom clean. ; Milking shed . A plentiful supply of both hot water (for sterilising and utensil washing) and cold water (for floor washing and milk cooler) is required in the milking shed. Whatever form the equipment takes, the principles governing the domestic water supply also apply to the cowshed. Pipe runs should be short and drains should contain as few bends as possible. The hot-water system should be non-ferrous throughout and runs well lagged. Consideration of the plumbing system in the planning of the milking shed is more profitable than adapting the plumbing to the building. ; Paddocks A well-planned farm water supply provides stock-watering facilities in every paddock not served by a natural water supply. This means the installation of drinking-troughs controlled by ball-cocks, by which the level is kept constant after intermittent use by stock, and of a capacity sufficient to provide for prolonged use. In a stock water supply it is preferable to provide storage in a number of drinking troughs of medium size placed around the farm than to concentrate all the storage in one large supply tank. For this reason drinking troughs larger

than those required to supply the stock economically may be an advantage. Though the most suitable size of trough will depend on the number of stock to be watered, the trough must be large enough to allow free drinking without undue congestion. As cows are the heaviest drinkers, troughs should be of volume sufficient to allow 4 gallons per animal per paddock, but this quantity can be increased with advantage, particularly if the feed flow is small. The shape and construction of stockwatering troughs vary considerably; wood or iron ones may be used, but the most satisfactory are made of concrete. Circular or square troughs have distinct advantages; they will cater for the needs of the greatest number of animals at any one time, and one trough can be used for two or more paddocks. If placed on the boundary between two paddocks, one half of the trough is available to each paddock; if at the corner of four paddocks, stock in each paddock can have access to a quarter of the trough. Details of the construction of both circular and square concrete troughs are set out in Bulletin No. 184, “Concrete on the Farm,” issued by the Department of Agriculture and available from any office of the Department. Fig. 26 shows a typical section through a reinforced-concrete trough constructed with an apron to prevent the ground round the trough becoming mucky. Garden and Orchard Water service for the garden and orchard includes the supply of water for such items as large-scale spray irrigation for crops and pastures, which is a method of supplementary irrigation that can be used? to advantage in nearly all humid areas on such crops as vegetables, small fruits, potatoes, and sugar beet and on pastures. This is made possible by the use of light-weight, quick-coupling pipes fitted with either revolving sprinklers or fixed spray nozzles. Points round the Homestead Though many farms have a good water supply system, the distribution round the homestead does not always receive the attention it should. There may be no outlet point near the barn or implement shed, and water for the fowl run may have to be carried some distance. Even where outlets are provided, the size of pipe used is usually too small to allow adequate flow, or the pressure may be too low to permit a hose to be used. Though outlet points round the farmyard may be kept at a minimum for the sake of economy, they should be placed to give the best service and should have ample volume and if possible pressure sufficient for a hose. Not all water services have the necessary pressure for a hose, but in the event of fire quick access to a hose, even if it is only of garden size, which can be connected to a handy tap outside the house or in the yard may be the means of averting disaster. The question of Obtaining enough pressure to operate a hose could well be considered when planning a water supply system. Any pressure above 201 b. per square inch gives a good velocity through a small hose nozzle, provided the volume is not restricted by too small a supply pipe.

Installing a Water Supply System T . . . , 1 ' . ~, ~ If properly planned the installation ow a good water supply . system is not difficult, though -certain tools are necessary. When the locations of the pump and reservoir have been decided and convenient positions for. the various troughs and outlets have been fixed, the lines for the pipes can be marked out - as planned and the trenches prepared. A single-furrow plough is suitable for this work, the finishing being done by spade. The depth should be sufficient to protect the pipes from frost and, where the ground is likely to be cultivated, from implements. A depth of 12 to 18in. is sufficient for most purposes, though the water will be cooler in summer if the trench is deener ™ ?a?!*™* ic ™ and the screwing together can be done the length of the pipeline increases the pipe can be laid along the trench, Invent* resting on battens till more pipes have ic n? fnr raffing plenty of room for swinging a wrench, and the male ends can be squared to the sockets to make screwing easier. Where a lead-off or branch is to be taken the pipe is cut to give the required length, threaded, and a rightangle bend or T piece fitted as 1 required. The pipelines are run merely by screwing pipes of the lengths required together with the required fittings. _ . : lools Though the range of tools required for pipe work is not great, the correct tools must be used. Fig. 27 shows some

pf the tools required. A hacksaw may be used instead of pipe-cutters, and p i pe .joint compound instead of redlead paint. The sizes of pipe wrenches, p i pe vice, an( d j es mus t be suitable o the pipe sizes being handled. For example, a 2 4in. wrench should not be used to turn a Jin . pipe , because the leverage would strain the thread; a i2in. to 14in. wrench would be more suitable „ ' ... ~ . • , When cutting pipe with either a backsaw or pipe-cutters the tool should P e hem square to the work, as shown Fig. 28, and the work should be clamped firmly in the vice. After cutting, particularly if a wheel-type pipe-cutter is used, the end of the pipe mus l be reamed or filed out to remove all burrs and restore the opening in the pipe to its original diameter. The removal of burrs from the outside and the provision of a small bevel on the CUt edge g Ve lead both to the dies when screwing . and to the finished thread, which helps in starting the thread in fittings. A hacksaw can be used dry but a whee l-type cutter requires oil to keep the cutters trim. Hacksaw blades with fine teeth (20 to 28 per inch) are better suited for cutting pipe, a s the teeth are less liable to tear ' . . , V ban a pipe 18 screwed with stocks and dies the dies should be the right sle . or pipe. If adjustable dies with loose chasers are used, the adjustment should be checked. The tail guide in the dies must also be the corfeet . size, otherwise a crooked or drunken thread will result. Fig. 29 shows the hand action used in screwing fin. diameter pipe with dies with fixed chasers. The dies must be pressed hard against the pipe while being turned in-order. to start the thread. A light engine oil should be

used freely to lubricate the dies while cutting. As the length of thread required for normal fittings on any size pipe is generally slightly more than the depth of the dies, it is not necessary to remove the dies to measure the thread; sufficient thread will have been screwed on when the back of the dies is just past flush with the end of the pipe. When the pipe has been cut and screwed and before fittings are applied the pipe thread should be painted with thick red-lead paint or treated with pipe-joint compound and a wisp of plumbers’ hemp wrapped round the thread in the direction of its travel, as shown in Fig. 30. The hemp should be smoothed out on the pipe with the fingers so that the paint or compound impregnates the hemp strands. This treatment for pipe threads should also be applied to the jointing of pipes already threaded. The sockets and keeps of the pipe should be removed, the sockets and pipe threads cleaned, and the pipes blown out. After treatment of the male threads with paint and hemp the pipes can be coupled together with the sockets. The female thread is sometimes treated with paint as well as the male, but this practice is not recommended, as an accumulation of paint may be pushed into the fitting and set hard before the water is turned on, thus restricting the flow and increasing friction head. Fittings such as T pieces, elbows, and bends can be screwed on to a pipe without any special precautions, but such parts as valves must be handled more carefully. Fig. 31 shows how a valve should be screwed on to a pipe. The valve should be gripped by the hexagon nearest the pipe; if the valve is gripped by the outside hexagon, the strain may distort the valve body and damage the mechanism. Fig. 32 shows the correct method of screwing a pipe into a valve. The strain should be taken with a wrench held on the hexagon nearest the pipe being screwed. The walls of some fittings are

very thin and care must be taken to avoid distorting them. When pipe runs are completed the pipe should be washed out well before the outlet control is fitted, as a blockage through dirt and chips when the service is in operation can be very annoying and may cause damage to tap washers. : General Precautions In installing pipe runs care should be taken to guard against airlocks (high points with no outlet where air can be trapped). This is particularly important on pump suction pipes, which should have an upward slope from the foot valve to the pump. Unavoidable airlocks on normal runs can be minimised by the provision of air valves at the high spots. Air travels upward through water and, being compressible, can cause surging and water hammer. The possibility. of excessive and ; dangerous pressures should be guarded against. Pumps working against high heads and hydro-pneumatic pressure systems with a reciprocating pump should always be provided with a pressure relief valve installed on the discharge side of the pump between the pump and any check or stop valve. The pressure relief valve should be inspected at least twice a year to ensure that it is always in working order. If a pipe is run from the valve back to the source of water or to a drain, flooding of the pump location will be avoided. Electric motors driving pumps should be equipped with overload and no-volt release switches. Pumps with long suction lines will probably require a snifting valve to permit the entry of a small quantity of air to facilitate valve cushioning. An air vessel on the suction side as well as on the delivery side can also be an advantage in such cases.

When pipes are laid in a trench the filling in of any section of the trench should be delayed until the water has been turned on at full pressure. This allows leaks to be detected readily and avoids the necessity of reopening the trench. “Weeping” (drip leaks) at screwed joints should cause no anxiety, as small percolations of water through a dry joint usually take up when the pipe is under pressure. Purification of Water As the provision of an adequate supply of reasonably-pure water is essential to the maintenance of life, the importance of purification cannot be over-emphasised. Impurity in water may be organic or inorganic and may occur either in suspension or solution. Though many substances and various types of bacteria may be present without constituting any danger to health, the presence of disease-bearing germs can render water. affected highly dangerous. When present in water in such quantity as to be dangerous inorganic impurity is often distinctly perceptible to the senses. For example, various salts render water hard and nauseating, and many of the iron compounds are obvious in both taste and colour. Generally ground water taken from certain depths is sufficiently free from bacteria to be safe because of the natural filtration that occurs in its percolation through the ground, but sur- . face water must always be regarded with suspicion. As most of the bacteriological contamination of water may be traced to human or other organic pollution, it is obvious that purification of a water supply becomes a serious problem when the density of human beings or animals is high. Water to be fit for human consumption must be free from suspended

matter, colourless, odourless, agreeable to the taste, and must contain no disease-bearing bacteria. Bacteria may be either removed from water mechanically by filtration or destroyed. A large part of the matters in suspension may be removed by passing the water through sedimentation tanks, in which the matters are deposited by their own weight. The most finely-divided suspensions, however, are the bacteria which, except those carried to the bottom of the tanks with the heavier suspended matter, cannot be disposed of in this way. For their successful operation filtration processes largely depend on the formation of a sediment layer on the surface of the filtering media, and group themselves into two classes — slow gravity filters and rapid gravity or pressure filters. With pressure filters, chemicals are usually added to the unfiltered water to produce an artificial layer of sediment rapidly, and the filtration may be much more rapid than in the case of the older, gravityfed sand filters. The destruction of the bacteriological content of the water is done by chemical sterilisation. Numbers of chemicals have been used with varying degrees of success, one being chlorine in the form of chloride of lime. The introduction of free chlorine compressed in cylinders in liquid form simplified its application as a sterilising agent. Automatic chlorinating plant is now available that will chlorinate water accurately for any demand. As the dose of chlorine is on an average appreciably less than 1 part in 2 million parts of water, the quantity of chlorine gas used is very small. Chlorine in sufficient quantity is an absolute sterilising agent, but because raw water may vary materially and rapidly in quantity of matter in suspension and organic content, a varying proportion of free chlorine is consumed in the oxidation of these substances. To ensure the continuous destruction of all bacteria it is there-

• • • fore necessary to treat the water with an excess of chlorine, and this excess may become apparent in taste and smell. Thus in a water supply for domestic purposes chlorine is best used as a preliminary to subsequent treatment in filters, as the rate of dosing should be restricted to a maximum which does not make the water at all objectionable to taste or smell. Where a water supply is fed from a river, creek, or well every precaution must be taken to ensure that pollution cannot occur or that disease-producing germs are carried into the water supply from drainage or other sources. If this possibility exists and cannot be eliminated, the installation of sterilising plant would be wise. Increasing Inadequate Water Supplies If the existing source or sources of water are inadequate, the supply may possibly be increased in a number of ways. The suggestions listed below should remedy the main causes of inadequate supplies of water. Weak Spring The flow from a spring may be weak for one or more of the following reasons:— , 1. Spring located above the dryweather water-table. 2. Spring hole not well cared for. 3. Spring flow dammed up. 4. Water being lost in the soil around spring. 5. Water being drained away to another well or spring nearby. If the spring is located above the dry-weather water-table or the water is being drained away to another well or spring nearby, there is no remedy except to use another source. The obvious remedy for a spring that has not been well cared for is to clean the hole and prevent the water from leaking away. If the vein becomes

covered with mud and leaves, the water may be diverted to other outlets. If the soil at a spring is porous, the water may sink as it flows from the vein, and this may be obviated by providing a watertight catch basin. The damming up of a spring is caused by an improperly-constructed storage basin. Many springs are located along the edge of layers of bed rock over or ■ through which the water flows to the spring, and the spring may be caused by a low place or crevice in the rock. In such a case the damming up of the water may divert it to some other outlet. The storage basin for a weak spring should be located far enough below the spring to permit free flow from the spring, as shown in Fig. 33. Where water is being lost in the soil around the spring a collecting tile should be used as shown in Fig. 34. Sometimes the water seeps out of a layer of rock along a considerable distance at the foot of a slope, forming a bog or swamp in the area of the spring. Drain tiles arranged as shown will collect this water and direct it to the spring. The tiles should be laid in gravel at a depth of 4ft. and covered with heavy clay to keep out surface water. The entire drained area should be fenced to keep out stock, and a diversion ditch should be dug above the area to divert surface water.

Inadequate Well

A well may be inadequate for one or more of the following causes:— 1. Not deep enough to penetrate water-table, or below free-ground water-level. 2. Filled with mud. 3. Not enough storage capacity. If a well is not deep enough to penetrate below the dry-weather water-

WATER SUPPLY . . .

table, it will become very weak or dry up in dry weather. Generally in regions where wells are common an adequate supply of water can be obtained if the well is dug or drilled deep enough. In some locations there is danger of striking salt, sulphur, or objectionable minerals at great depth, but usually at least the quantity of water can be increased. If the well has been dug, the best method of going deeper is to drill through the bottom. In drilled wells the old hole may be extended by additional drilling. If the well is old, the flow may be obstructed by an accumulation of sediment in the bottom. In a dug well this may be bailed out with a bucket, but in drilled wells a well-driller’s bail should be used after the drop pipe has been removed. It is never safe to “shoot” a well with explosives, as there is just as much danger of losing the existing supply as there is of increasing it. Fig. 35 shows how sediment in the bottom may restrict the flow in a drilled well. The use of explosives in any attempt to clear it might force the sediment into the water-bearing stratum, thus clogging the pores and further decreasing the flow. Moreover, explosives may open cracks in the bed rock and allow the water to flow away from the well instead of into it.

If the well has not enough storage capacity, its diameter, depth, or both should be increased, though in some cases it is cheaper to dig another well. Roof Catchment of Rain. An inadequate supply of water in a system of roof catchment of rain may be caused by:— 1. Not enough tank capacity. 2. Not enough roof area to catch water. 3. Gutters and down-spouts in poor condition. 4. Not enough rainfall. 5. Leaks in the tanks. Sometimes the area of roof used for catching water is insufficient to give an adequate supply. This can be remedied by providing additional gutters and down-pipes on the remainder of the roof. The only remedy where the rainfall is inadequate is to provide additional roof area and storage to catch and hold what rain does fall. Nowhere in New Zealand is the annual rainfall insufficient to provide an adequate water supply if sufficient roof area and storage are used. Supplementary Supply Any inadequate water supply can always be supplemented by drawing

: water from two or more sources to i supply the one system. For example, ! if a lake, pond, or stream is available either for gravity flow or for pumping, it can be tapped to increase the supply from an inadequate well or spring, ! though two pumps and two separate piping systems should be used so that the well or spring water can be used for domestic or any other purpose requiring good water and the lake, 1 pond, or stream water can be used for watering stock, sprinkling, irrigation, • or sewerage if water-closet drainage is installed. A rain-water supply for domestic purposes can be used in this dual method. t References - “Rural Water Supply and SanitaL tion,” by Forrest B. Wright, Ph.D., Assistant Professor of Agricultural Engineering, New York State College I of Agriculture, Cornell University. J “Agricultural Engineering” (the 1 journal of the American Society of r Agricultural Engineers). ' “Farm Mechanisation,” published by I Temple Press, London. “lowa Farm Science,” published by lowa State College, Arnes, lowa, U.S.A. “Water Supply,” Bulletin No. 235 of i the New Zealand Department of Agri- » culture.

TYPES OF DAMS

CUTTING, SCREWING, AND JOINING PIPES

A HOME-MADE TRACK GRADER

By

A. J. LYNCH,

Assistant Instructor in Agriculture,

Department of Agriculture, New Plymouth.

MOST farm implements contain a few sound parts which fall into disuse when the implement is discarded, but such pieces of derelict machinery can often be resurrected from the scrap heap and put to good if novel use. The efficient farm track grader illustrated was made by Mr. L. George, of Tarata, Taranaki, from parts of sets of disc harrows and other odd pieces of machinery.

THE essential difference between the new machine and the original is that a grader blade is now carried in place of the set of discs, but that required some improvisation on the part of the maker. The blade, an old one salvaged from a road grader, is bolted to two 6ft. planks of Bin. x 3in. timber butted edge to edge. The cross-piece which originally supported the discs now supports this blade by a vertical strap of 2in. angle iron (also parts of a disc set) at each end. The attachment of the vertical straps to the cross-piece is adjustable so that the blade can be worked at different depths. The grader blade must also work at different angles to the direction of ‘ travel and must therefore pivot at a i central point. A 12in. x Bin. steel plate is bolted to the top of the chassis directly under the cross-piece, and a steel bolt passes through a central hole in plate and cross-piece. This is the only direct attachment of the crosspiece to the chassis. However, the

blade must be supported at each side or it would pivot freely on this plate, and from some old car springs found lying idle two stays 4ft. 6in. long were made. They run from each side of the blade to the front of the chassis, and the angle of the blade is regulated by adjusting the length of these. Each stay has a half twist to facilitate fitting.

Mr. George’s farm is broken and many hillsides are excavated for cattle tracks. In the winter and spring they cut up badly and as a result are very rough in summer, but with this grader they can be levelled off and used safely by all stock and farm vehicles. The problem of keeping clay races and tracks in good order is present on many farms. This machine is very efficient and of very light draught even on hard papa-clay tracks, and the cost of construction was almost negligible, as it was made entirely from disused parts of other implements.