Water is the most basic requirement for survival. It is needed for drinking, cooking, washing, and watering plants.
Quantity of water required:
It is handy to know how much water is required from a domestic supply such as a dam, a bore or a roof-water tank so that the right size and place for each can be found. Water is measured in litres for most farm applications. A flow of water in a pipe is measured in litres per second. The quantity of water required for various purposes is measured in litres per day.
It is impossible to give exact amounts of water for various purposes because climate and habit frequently dictate the requirements for water. However, the following table gives a general guide to what is required.
Further information concerning estimates of the water requirements for these and other uses can be obtained by contacting the local office of the Department of Agriculture, or the Farm Water Supplies branch of the Water Resources Commission, North Sydney. Before irrigating seek advice. Irrigation generally requires a large amount of water to achieve a good result.
Rain water tanks:
The most obvious way to obtain a domestic supply of water is to collect roof-water in a tank when it rains. Tanks can be above or below ground. They can be made of concrete, galvanized iron or, if in the ground, lined with bricks, clay or plastic.
Commonly, roof-water tanks are fitted with a lid to discourage evaporation which seriously depletes water supplies in many parts of the State. The lid also keeps light out and discourages algal growth in the water. Algae can render a water supply unpalatable.
Activity Water required:
(L/person/day)
Drinking, cooking, washing up 15
Washing clothes 25
Bathing 80
Flushing toilet 35
Other activities including cleaning teeth, washing
floors, general cleaning 25
TOTAL 180
Animals Water required:
(L/animal/day)
Lactating cows 70
Other adult cattle 45
Calves 25
Working horses 55
Grazing horses 35
Sheep on dry pasture 5-14
Pigs (other than sows) 10-20
Sows 25-60
Laying hen 0.3
Dams:
Stock water supplies usually need to be larger than domestic supplies. An obvious way to supply water to stock is to have a small dam. A dam requires a catchment (some land which drains into the dam). The dam must be large enough for the purpose and have a catchment which is large enough to supply the water required.
There must be sufficient water for stock after evaporation has taken its toll. Professional advice on the size of storage which you require may be available from the Water Resources Commission but for small storages professional advice may not be needed.
At some time all dams will overflow and provision should be made for this to occur safely. It is an offence under the law to concentrate water which subsequently damages someone else’s property. An earth “by-wash” or by-pass channel may be a satisfactory way to avoid collapse of a dam caused by flood waters rushing over it.
Not all soil is suitable for building a waterproof embankment. If the soil is too sandy or the clay is not of the right kind, or if the soil is not well-compacted, the dam will leak and may eventually fail embarrassingly, or even disastrously.
It is sometimes possible to prevent water leaking through or around dams by lining upstream areas with clay, or bentonite (a clay that swells when wet) or various chemicals. However, it is easier and cheaper to construct a dam properly in the first place. There are few soils that do not respond well to compaction during construction.
Compaction is usually achieved by rolling the soil in thin layers as the dam is built.
Bores:
A bore is an attractive way to obtain water since it does not rely directly on falls of rain to replenish the supply. However, bores are often very expensive, and, if the water is in a deep layer, the cost of pumping will be substantial. Not all areas have bore water of suitable quality and quantity at shallow depths.
The Hydrogeological Branch of the Water Resources Commission keeps records of bores in the State and can give an assessment of your prospects of obtaining suitable water and its likely depth. The Commission will also drill bores. The costs of a bore vary according to a number of factors not usually known until after construction.
Bores are required to be licensed by the Water Resources Commission. Bore licences are free and are intended to provide information to the Commission. A dam requires a licence only if it is bigger than 7 ML capacity or is on a watercourse that supplies downstream users who will be affected by the storage, or the watercourse is one which has a flow for mote than a few days after rain.
If in doubt a licence application should be lodged with the Commission. A deposit of $24.00 is required on application. The initial fee may form part of the first licence fee if a licence is subsequently granted.
Streams:
Water can sometimes be obtained by pumping from the water flowing in a river or stream. The pump is required to be licensed by the Water Resources Commission unless the water is used only for stock and domestic purposes.
Pumps:
Almost always the water you require will not be where it is wanted. To get it where it is required, a pump has to supply the energy needed to pump water uphill and to overcome the friction of the water on the walls of the pipe. Clearly, if a small pipe is used to carry a quantity of water, it must move through the pipe more quickly than if a larger pipe is used. The faster the water moves, the more resistance there is to the flow. The extra pump pressure required to overcome this resistance to flow costs money in energy.
Over the life of a pump and pipeline, it is generally better economy to instal larger pipes which cost more initially but the investment is amply repaid by lower energy costs. Pump suppliers can assist in determining the correct pump and pipeline for your requirements.
The power source for a pump is usually diesel fuel or electricity. If a pump is very small and infrequently used, a petrol motor may be suitable. The running cost of fuel engines is generally at least twice that of electric motors, though this varies from area to area.
Windmills:
Windmills can be used for pumping small quantities of water but are very expensive to buy and must be associated with a storage from which water will flow under gravity for more than a week when the wind is not blowing.
Domestic supplies:
Domestic water supply systems often use a centrifugal pump to supply water automatically under pressure directly to the taps. When the pressure in the system reaches a certain level the pump is stopped by a pressure switch. Water can be drawn off from the system as required. As it is drawn off the tank progressively empties, the air in the tank expands and the pressure in the system drops. When the pressure reaches a certain lower limit the pressure switch starts the pump and the process is repeated. The system is excellent but relies on the availability of electricity.
Managing Farm Water Quality:
The number of good quality water supplies for agricultural use has rapidly decreased over past years because of the intensive use of our limited water resources, and the increasing competition between domestic, industrial and agricultural users. For this reason, many marginal or poor quality waters are now being used. Farmers are increasingly concerned about the damage to soils, crops and stock caused by these waters.
The Department of Agriculture offers a comprehensive Water Quality Assessment and Treatment Service to help New South Wales farmers obtain maximum crop production. If in doubt about the quality of the water on your property, bring a sample of about 500 mL in a clean plastic bottle to the local office of the Department.
The report on the test will indicate whether or not the water is suitable for stock and irrigation. If you require a more comprehensive biological report on its suitability for human consumption, contact the Health Department of your shire or municipal council. They will tell you how to take samples in a sterile manner.
Various quantities and types of dissolved salts (ions) are present in all irrigation waters. Crops, soils and irrigation equipment can be adversely affected by the presence of too much or too little of one or more of these ions.
Salinity and plant growth:
Plants are affected by high levels of salinity in different ways. The ability of the plant to take up water is likely to be reduced; there may be toxic amounts of specific ions present; or an imbalance of ions may induce the deficiency of one or more nutrients.
Water stress:
Salinity may be so high that some sensitive plants are unable to adjust. When the rate of water uptake by the roots is reduced to less than the amount lost by transpiration, plant tissues dehydrate and growth is reduced.
Plants suffering from salt stress typically look stunted with small, dull, bluish-green leaves and heavier deposits of wax, but there is seldom any wilting. This is in complete contrast to plants suffering directly from water stress.
Specific ion toxicity:
Sodium ions and chloride ions at rather low levels affect trees and woody ornamentals whereas annual crops are not affected. Certain trace elements in toxic levels can also affect a wide range of crops. Chloride toxicity produces foliar damage—leaf scorch and tip die-back.
Defoliation may follow. High chloride levels in soils can be removed by leaching. Appropriate choice of crop plants, or root stock or variety suited to the chloride level should be made by consulting Department of Agriculture officers.
Chloride toxicity caused by foliar absorption is more damaging than absorption through the roots. This may occur when overhead sprinklers are used on hot, dry days. Irrigation at night will minimize the problem if higher levels are present.
Ion imbalance:
A sodium hazard in water is an imbalance of the ratio between sodium and calcium. This can lead to soil structure problems namely crusting, poor water penetration, low aeration levels and poor drainage, particularly with clay soils. It can also cause sodium toxicity to some plants particularly when using overhead sprays.
The sodium hazard to soil structure and plant growth can usually be reduced by adding gypsum to the water. Seek advice on the amount to use. Chemical analysis of the irrigation water will tell whether there is a potential salinity problem. Salinity problems occur when the water contains more salt than a specific crop can tolerate.
Lists of plants and their tolerance are available from agronomists and horticulturists of the Department of Agriculture. Examples of sensitive crops are beans, strawberries, carrots, stone fruit and citrus trees. Cucumbers, tomatoes, watermelons and carnations are examples of the moderately tolerant group of plants.
Most of the problems associated with the use of marginal quality water arise from the incorrect operation of irrigation systems, for example, pressure too low, sprinklers rotating too slowly and poor distribution patterns, coupled with other factors such as allowing the soil water to dry up too much between irrigations, and not knowing the water requirement of the crop.
Salinity and animal production:
With animals, the tolerance of salinity of drinking water varies with the species. Water which is only just fit for animals may become unsatisfactory during summer because stock drink more in hot weather, feed is usually drier in summer, and the salinity of some water increases due to evaporation.
Young animals, lactating females and weakened or aged animals are more sensitive to dissolved salts than healthy, dry, mature animals. Stock can tolerate water of higher salinity when on green rather than dry pasture. Stock accustomed to saline water can tolerate higher levels of dissolved salts. Stock used to fresh water may drink excessively if introduced suddenly to a saline water, and suffer ill effects.
With animals such as pigs and poultry fed mainly on prepared feeds, the salt content of the feed should be reduced if the water is saline.
Hardness:
High levels of calcium and magnesium salts make water hard. Hard water can deposit salts and eventually block irrigation equipment and hot water systems. The calcium and magnesium in hard water used domestically react with soap to form insoluble scales seen as greasy, dirtattracting scums on baths and on washing utensils. The treatments for hard water are ion exchange resin softener, non-soap detergents and chemical water softeners.
Corrosion and soluble iron problems:
Corrosion of metals occurs because of many factors, including acidity, level of calcium bicarbonate, dissolved oxygen, electrical currents and biological action. However, acidity of the water is the most common cause of corrosion. Addition of lime to bring the pH to 7.5 will minimize the problems.
Soluble iron is usually associated with deep bores and dams where oxygen is limited. If present it can stain plant leaves, baths and sinks. It can also block irrigation systems. Control involves aeration and settling before use.
Clarification of water:
Muddiness caused by clay, silt and other suspended matter can be clarified with a flocculating agent such as alum or ferric alum at a rate between 0.40 to 0.75 kg per 10 000 L to bring particles close together forming larger particles that will settle out. As the addition of alum increases the acidity of the water, add lime at one third of the amount of alum used to neutralize the effect of the alum.
Colour, taste and odour:
Chlorination, clarification and removal of iron and algae will assist in removing some tastes and odours. An activated carbon or cartridge filter (available commercially) may be used as a final step to ensure palatable water supplies.
Contamination by algae and bacteria:
Increased nutrients in water encourage the growth of algae and bacteria. To avoid this problem, reduce the flow of contaminants to water courses and storages. Position septic tanks so drainage does not flow directly into water supplies. Graze stock so urine and faeces do not enter water supplies.
Fence off dams.
Treat the contaminated water in tanks by chlorination to kill microorganisms. Preferably, the quantity of chlorine required is determined by testing a sample of the water. However, in clean, clear water about 10 mg of chlorine per litre of water may be used.
To kill algae, spray copper sulphate (bluestone) at the rate of one gram per 1000 L. Remove dead algae because they can be toxic to stock. Do not use copper sulphate when fish are present as it will kill them. When in doubt, check it out Most water supplies you will encounter on small properties will be suitable for stock, irrigation and use round the house. Make some inquiries of the neighbours and if in doubt, take a sample in a clean bottle to the nearest office of the Department of Agriculture.
You should be more particular about the quality of water if you intend to drink it. A sample submitted to your local shire or municipal council should allay any doubts you may have.
Fish In Farm Dams:
Intensive research conducted by the New South Wales State Fisheries at the Inland Fisheries Research Station at Narrandera has provided information on stocking farm dams with fish. Much is now known about suitable species, growth rates, stocking rates, nutrition, dam sizes and cultural practices, and research is continuing.
Suitable dams:
Fish will survive and grow in very small bodies of water provided adequate food is available. However, dams of one tenth of 1 ha (1 000 m2) in surface area, or larger, will give the best results. Most of the food for fish in a dam is produced on the dam walls. Dams with gently sloping sides receive more sunlight and therefore have a greater food production potential than deep dams with steep, shaded sides.
It is not necessary for a dam to have water flowing in continuously. All that is needed is a suitable catchment or provision to top up to prevent
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