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Our uses for water include: drinking, cooking, preparing medicines, sanitation, diluting disinfectants, decontamination procedures, and the washing of our bodies, clothing, utensils and habitat.
The body of an eleven-stone man contains just under ten gallons of water. It loses about a pint a day by evaporation from eighteen square feet of surface area. This is when it just sits still and breathes lightly. When its sweat glands start to work the amount which needs replacing is about six times as much. And its normal foods require about three pints daily for their cooking.
Though water contains neither calories nor vitamins, we need it not only in large quantities but clean. Only oxygen is more essential to our survival.
In addition to the fixed water system of the house or other buildings, and to water in recepticles filled at the last minute, large supplies of water should be located in or near shelters for use during the refuge period. Inside buildings, such tanks or barrels should be placed where the structure of the building is best suited to supporting their weight, bearing in mind that this strength may be reduced by blast damage. If sunk into the ground outside a purpose-build shelter, to conserve space within the shelter, it will need either a pump or to be higher than the shelter to allow natural flow. If it is to be siphoned by mouth, the connecting pipe will need to be of narrow diameter. Provision must be made against air-locks occurring as the water level in the tank drops. This can be effected by a narrow air-pipe leading into the tank, fitted with a filter and, as with all ventilation pipes to the surface, extend upwards at least six feet above ground level to be clear of heavy gases collected there.
Upon emerging from shelters, supplies taken in initially will probably be exhausted. The immediate need for water may be satisfied by what remains in buildings. This supply will be pure if the tanks were adequately covered and the water system undamaged. It may be necessary to remove air-locks by opening a tap on the top floor and then draining the pipes from the lowest point in the system.
Depending on the season, efficient collection of rain-water may meet the most pressing needs. The roof of a building forms an ideal catchment area. This may be added to by flooring any piece of ground with tarpaulin or sheets of plastic, with cemented brickwork, concrete, slates or even puddled clay.
The immediate need for moisture may also be met from hard-skinned fruits including rhubarb, provided these are ripe and first wiped free from fallout and other contaminants.
A further immediate source of water, but which may be contaminated if damage has been sustained anywhere along its route, would be the public water supply. Access to this may be had by digging down to mains beneath the roads, should re-opening the stopcock by the front gate prove unrewarding. But this might delay the laying-on again of the most essential of public facilities, and only in exceptional circumstances would water not be available from other sources including rain and snow, rivers, lakes and reservoirs, springs and wells or even the sea, this would be advisable and, in the long run, even counter-productive. It should also be remembered that unauthorised tapping into the public water supply amounts to theft and contravenes laws, including those covering public health.
Which among these other sources should be used will depend on their location. For reasons of avoiding fallout, it may be preferable to minimise movement and, except in places where collected rainfall by itself suffices, to obtain water from a well.
Except in city centres where almost all ground is paved and the rainfall removed by the drainage system, rain seeps down through the soil until it reaches a layer of impervious clay or rock on top of which it collects. This level, the depth of which varies with local geological stratum, is called the water table.
How long the water supply at this level will last at any point depends upon how many people are taking from it, and on economies exercised. However, when it is exhausted there may be further supplies at a deeper level, caught by a wider impervious layer. Where and at what depth these various layers exist should have been checked from geological maps of the area and have been marked on ordnance survey maps.
Siting a well. This may have to be a compromise between the risk from fallout and other hazards involved in collecting water from a distance, and that of pollution if it is near a sewage outlet. In controlled areas a licence is required to open up a well, under the Water Act 1945.
Digging a well. There are two precautions to be taken: (a) that the sides to not collapse. This is normally prevented by lining with timber, galvanised iron, cemented brickwork or concrete. If these or other suitable materials are not available, and as soon as there is any sign, such as seepage of water into the hole, that the sides are no longer stable, these should be widened at the top so that in section the well takes on a funnel shape; (b) that the impervious layer, which may be thin, is not inadvertently dug through with the result that the water resting on it drains away.
When the water table has been reached, at least the lower parts of the well should be lined as firmly as possible. This lining sleeve should have sufficient gaps in it to allow though it the flow or seepage of water.
Bear in mind that should water at this level become exhausted so that the depth may have to be increased, the diameter of the lined section must allow for further excavation.
Drawing water. In deep wells it may be necessary to do this either by crossing the top with timbers and placing a windlass on these, or by the cutting of steps round and down the funnelled sides. The trouble involved in constructing a windlass may be offset by the time saved by its use in raising and lowering those digging the well, and in removing the soil from it.
Protecting the well. The well should be roofed-over to prevent fallout entering it. From a shallow well a roof will also reduce loss from it by evaporation. You may also need to camouflage it with rubble.
Although water is not harmed by radiation passing through it, it may be poisoned by fallout and, in towns especially, by chemical or biological weapons, ruptured sewers, makeshift sanitary arrangements, rats and other factors.
The degree to which these micro-organisms in the soil, which under normal conditions add to the natural effectiveness of the soil as a filter, would be affected by fallout carried down into the ground by rain, cannot yet be judged.
Once, though, a water supply of sorts is found, priority passes to making it safe to use. There are five basic ways of doing this: by chemical additives, by sedimentation, by filtration, by storage and by heat, or by a combination of these.
Chlorine is a yellow-green, bactericidal, heavier-than-air gas which is obtainable in cylinders of 100 lbs. and upwards. Under pressure in excess of 85 lbs. per square inch it is liquid. When this is fed into the water supply through a chlorinator, the liquid becomes gas.
For piecemeal treatment of water during a fallout period though, chlorine may be used as follows:
(a) As the white powder chlorinated lime/chloride of lime/bleaching powder, resulting from the treating of slaked lime with chlorine gas, 15 mg. should be added to a gallon of water.
(b) As liquid household bleach, sixteen drops are added to a gallon of water, stirred well and allowed to stand for half an hour. Most bleaches contain about 5.25% sodium hypochlorite, and provided they do not also contain any other active ingredient may be safely used.
Trace amounts of sodium thiosulphate may then be added until the unpleasant taste of chlorine has been removed. This is usually available in 5.5 mg. tablets.
If, after chlorination but before the use of such as sodium thiosulphate, the water has no smell or taste of chlorine, it should be treated again. The absence of its taste or smell may mean that the chlorine has been insufficient or had deteriorated.
Iodine in tablet form is available for the purification of water. But two dozen drops of its tincture added to a gallon of water, stirred, and left for half an hour are as effective.
Permanganate of Potash. When sufficient of these purple crystals are added to water water to turn it slightly pink - a solution strong enough to kill bacteria - it has two advantages over other additives. If the water still contains organic impurities then the pink shade quickly fades, providing a rough test for purity. And when left to stand, it eventually oxidises itself.
Commercial products. For purifying small quantities of water for drinking purposes there are many products on the market. Sterotabs are made by Boots, and contain p-carboxybenzenesulphondichloroamide in 4 mg. tablets. Puritabs are made by H.T.Kirby & Co. Ltd of Mildenhall, and contain sodium dichloro-s-triazinetrione. Halazone is available in 4 mg. tablets which suffice to treat between a pint and a quart of water - according to its contamination - in an hour.
In this, chemicals such as alum/aluminium sulphate, ferric chloride or ferric sulphate, and lime in th3e form of calcium oxide or calcium hydroxide, oe even starch are stirred gently into the water until they are likely to have touched and collected into large particles or flocs most of its impurities. After half an hour the water is left to stand for two or more hours until the flocs have settled. The water is then removed from the container separately from the sludge or sediment, by a tap or by siphoning.
This flocking or chemical coagulation hastens and makes more effective the basic process which would occur anyway were the water to stand for several weeks.
This involves water passing through some porous material which will separate impurities from it. The material may be gravel, crushed anthracite, glass fibres, hessian, wool, cotton, whatman or other suitable paper and most thick cloths. Diatomaceous earth, i.e., of crinoid or fossil origin and which contains a high proportion of silica, should it be to have is very effective. So also is charcoal. But because of its availability, sand is the medium for use except where water is required only in small quantities for drinking in emergency.
Sand filters. The first requirement is a watertight container with a drainage hole in its bottom. Household baths are shallow for the purpose, and the main water-tank taken down to ground level from the loft more suitable.
The bottom of the container is covered by several inches of pebbles, on top of which a layer of gravel is placed. Then about six inches of course sand, followed by two to three feet of fine sand. When the drain at the bottom of the container has been connected to a receptacle at a lower level the filter is complete.
For the first three days water passing through this filter should be put aside and be passed through it again after a film of slime, zoogloea, has formed on top of the sand, and which will filter out most bacteria. When this film becomes so thick that little water can pass through it, the top two inches of sand should be replaced.
This permits bacteria and fallout in water, respectively, to die or to decay.
This is not a suitable method for the treating of large quantities of water, due to the amount of fuel required. It also gives the water a flat and insipid taste.
Boiling. If water is boiled for five minutes, most bacteria in it will be killed. This method has the disadvantage that in reducing the volume of water it concentrates any impurities which it has not destroyed. The wastage of water involved is partly offset by economy of soap resulting from softening of the water.
Distilling. This consists of turning water from a liquid into a vapour, in which form it is caught, colled and condensed back into liquid. This is carried out in a retort, a flask with a long bent neck, usually of tin or copper, or similar apparatus. It can be followed by rectification, which means repeating the process. Distillation is one of the most effective means of separating water from its impurities, and is the only means by which seawater can be made drinkable. However, distilled water is not only rather unpleasant to drink, but likely to produce stomach disorders. Water which has been used for cooking or washing may fairly safely be used again, even for drinking, if distilled and rectified though, if it is then aerated. So, in exceptional circumstances, may urine. The residue from distillation should be disposed of with care, for it may contain poisons.
Aeration. Water which has been distilled or boiled should be aerated. This removes hydrogen sulphide, smells such as chlorine or rotting vegetable substances, and some manganese and iron. This can be done either by bubbling air through the water, or by spraying the water through air. Small quantities of water can be aerated by pouring them repeatedly from one container to another. For larger quantities a simple apparatus can be built. This may consist of slag-filled trays placed one over the other so that the water trickles through each in turn. Or of a series of rough-edged steps; as the water flows down them it is broken up.
When several of these processes are used together, the preferred order would be sedimentation, filtration, chemicals, storage and aeration. In times of epidemics, drinking water should also be boiled or distilled, before the aeration stage.
A water reserve in the form of an open pond may be conserved by erecting round it a screen. This will not only shade it from the sun, but also prevent wind from replacing the moist air above it with dry air which would promote further loss by evaporation.
When water is held in containers of materials though which evaporation can take place, such as canvass water-bottles, this evaporation occurs more slowly through a flat surface than through one which is convex. Hence convex sides will tend to cool the water, but flat or concave sides will tend to conserve it.
Apart from boiling, much of the soap-wasting hardness of water can be removed by adding to it some slaked lime which, having disposed of the hardening bicarbonates of magnesium and calcium held by carbon dioxide, will settle with the other sediment. Slaked lime/hydrated lime/calcium hydroxide/Ca(OH)2 is simply lime on which water has been sprinkled.
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