Water in the Field

Lesson Overview

Water is the first concern of field health. Of all the illnesses that disable a force, the water-borne ones are commonest, above all the diarrhoeal diseases, because everyone must drink several times a day and a single fouled supply can sicken many people at once. This lesson covers how to choose the best available source, how to treat doubtful water by boiling, chemical disinfection, and filtration, how to store treated water so it stays safe, and how to run a clean drinking-water supply at a camp or welfare point. One truth runs through all of it: clear water is not clean water, and all doubtful water must be treated.

Field health is prevention, and water is where prevention begins. It is the partner of Combat First Aid: that course cares for those already harmed, this one keeps harm from arising. For a small, lightly armed humanitarian home-defence force whose purpose is to help the population through floods, storms, and other disasters, safe water is no afterthought. The people the Army is sent to help are exactly those most likely to be without it, and the very young, the old, and the sick will fall ill first if the water fails. Providing safe water is a leader's duty.

By the end you will be able to explain why water is the first concern of field health, choose the best available source, treat and purify water in principle by boiling, chemical disinfection, and filtration, store treated water so it cannot be recontaminated, and set up a safe drinking-water supply with the clean kept strictly apart from the dirty.

This is the knowledge layer. Treating water, testing it, and running a clean water point are reinforced and certified in person, under qualified supervision; any clinical care for those who fall ill belongs to Combat First Aid and to qualified medical staff. Where this lesson names a sign of illness or a measured dose, it does so for recognition only, so you understand the method and know when to call for help, never so you treat the sick yourself or mix chemicals unsupervised.

Key Terms

• Potable water: water that is safe to drink, having been treated and kept clean, as opposed to raw or doubtful water.
• Raw water: water taken from a source as found, before any treatment; always treated as unsafe until proven otherwise.
• Water-borne disease: illness, above all diarrhoeal disease, spread by water contaminated with disease, very often by human waste.
• Treatment, or purification: making doubtful water safe to drink by boiling, chemical disinfection, filtration, or a combination.
• Disinfection: destroying the disease-causing organisms in water, chiefly by heat or by a chemical such as a purification tablet.
• The water point: the place at a camp or welfare site where treated, safe water is drawn, kept clean and apart from any untreated water.
• Suspended matter: the mud, silt, and floating material that makes water cloudy; it can be settled or filtered out, but removing it does not make the water safe.
• Residual, or chlorine residual: the small amount of disinfectant left in chemically treated water after the organisms are killed, which goes on guarding the water and can be measured to confirm treatment has worked and is holding.
• Contact time: the full waiting period treated water must stand before it is drunk, during which the heat or chemical does its work; cutting it short leaves the water unsafe.

Why water comes first

Water is the route to guard first, and the reason is plain. A person can go without food for a long time but must drink every day, and often; whatever is in the water goes straight into the body, several times over, for everyone who shares the supply. That is why water-borne disease is the commonest field illness. The diarrhoeal diseases sweep through camps faster and disable more people than almost anything else, and they do it quietly, because a supply can look and taste perfectly good and still be deadly.

The cause is nearly always the same: human waste has reached the water. Illness leaves one person in their waste; the waste reaches the water by seepage, run-off, or careless fouling near the source; the water carries it into the mouths of many. One sick person upstream, one fouled bank, one latrine sited too near the supply, and a whole unit or relief site can be poisoned from a single source. So the first question of field health is always the same: is the water safe, and if there is any doubt, has it been treated?

Hold this chain of harm in mind, because every measure in the lesson breaks one of its links. Disease leaves a sick person in their waste; the waste reaches water; the water carries it, invisibly, to wherever it is drawn; a person drinks, falls sick, and becomes a new source in turn. The danger is that the chain loops, so one case becomes an outbreak, and in a crowded camp it loops fast. Choosing a clean source attacks the chain near the start. Siting the latrines away from the water, the subject of Lesson 04, attacks the link where waste reaches water. Treatment attacks the carrying water. Safe storage and a well-run water point stop clean water being fouled again. No single measure is enough alone, which is why the lesson insists on every one.

Recognise the diarrhoeal illnesses, but never treat them yourself. The picture is loose and frequent stools, often with cramps and sometimes vomiting or fever. The real danger is not the discomfort but fluid loss: a person with severe diarrhoea, especially with vomiting or fever too, loses water and salts faster than they can be replaced and may become dangerously dehydrated within hours, the very young and the old soonest. Blood in the stool, high fever, or the signs of serious fluid loss (dry mouth, sunken eyes, little or no urine, dizziness, deep tiredness) mark a case that needs medical help without delay. Your part as a soldier is to notice that something is spreading, report it, keep the sick person drinking safe fluids, and find and fix the water, because where one person is ill from the supply, others are about to be. The care of the sick belongs to Combat First Aid; the prevention is taught here.

Choosing the best source

The safest water is the water that needs the least making safe, so choose well. Treat every field source as unsafe until judged, then pick the cleanest water within reach by a few simple rules.

Prefer running water to standing water. A flowing stream or river carries contamination away and is generally cleaner than a still pond, where filth settles and disease breeds. Draw from a stream well upstream of any place where people bathe, wash, water animals, or relieve themselves: what enters the water above you will reach you, so put yourself above the dirt, not below it. Ground water from a protected well or spring is often cleaner than surface water, but only if it is set well back from any latrine, soakage pit, or other fouling. Avoid water that is cloudy, coloured, or foul-smelling, and any source the surrounding ground shows to be fouled.

Make the judgement in four looks:

• The kind of source. A protected ground source, a well with a sound cover and apron or a spring rising from clean ground, is generally best, because the earth has filtered the water. Among surface waters, prefer a clear running stream to a sluggish one, and either to a still pond or roadside pool where waste settles and the water may have stood for weeks.
• Upstream and uphill. Contamination travels down, so trace the water back. A settlement, a field with animals, a track crossing, or a latrine above your intake all warn you off.
• The ground around the source. A bank churned by feet or hooves, ground stained or smelling of waste, or a fouled margin at the water's edge marks a source already spoiled.
• The water itself, which tells you least. Clear water may still be deadly, but water that is cloudy, oily, discoloured, or foul-smelling is a clear warning. Any unnatural colour or a chemical or fuel smell rules a source out altogether, because the treatments in this lesson handle disease, not poison.

A short ranking holds the rules together. Take sources in this order, remembering that even the best is still treated before it is drunk.

   CHOOSING A SOURCE  (best at the top; all are still treated)

   best   protected well or spring, set well back from any fouling
     |    clear running stream, drawn well upstream of all other use
     |    a larger river, drawn upstream and well in from a clean bank
     |    rainwater caught clean off a clean surface
   worst  a still pond or pool, or any water near a fouled bank
          (avoid water that is cloudy, oily, discoloured, or smells wrong)

No source is trusted on its appearance. Clear water can be deadly, and the cleanest-looking spring can carry disease from a fouled source above it. Choosing well reduces the load on treatment; it does not remove the need for it.

Treating and purifying water

When water cannot be had from a known safe supply, and in the field it rarely can, it must be treated. Three plain methods make doubtful water safe, and you should understand all three. They are partners more than rivals: on a real task they are often used together, the cloudy water settled or filtered to clear it, then disinfected to make it safe.

Before any of them, deal with the mud. If the water is cloudy, let it stand in a still container until the suspended matter settles, then pour off the clear water from the top, or pass it through a filter or clean cloth to take out the worst of the silt. This matters because clearing makes the disinfection that follows far more reliable: cloudy water shields the organisms from heat and chemical alike and uses up the disinfectant on the mud. Clearing is the preparation, never the whole treatment.

The first and surest is boiling. Bringing water to a rolling boil destroys the organisms that cause water-borne disease, and where fuel and time allow it is the method to trust, because it needs no chemical, no measuring, and no special kit beyond a vessel and a fire. Let the water reach a true rolling boil, where the bubbles rise fast and break across the whole surface, not the first lazy bubbles at the side of the pot, and hold it there. The heat does the work, so the method does not depend on getting a dose right, which is its great merit when conditions are poor. Its one weakness matters: boiling leaves no residual, so boiled water has no protection against being fouled again. Cool it with the lid on and keep it covered and clean afterwards. A faint flat taste is normal and harmless; letting the water stand, or pouring it gently between two clean containers, restores it.

The second is chemical disinfection, most simply by the purification tablets the Army issues for the purpose. The method is exact, and the exactness is the point. Fill the container with the cleanest water available, clearing it first if cloudy, then add the correct dose for the quantity of water, set by the instructions and never guessed, because a small canteen and a large one need different amounts. Cap and shake so the tablet dissolves and reaches every inside surface. Then loosen the cap, tip and invert so a little treated water runs out around the threads and wets them, because the threads and lip are where untreated water hides and would recontaminate the lot at the first drink. Tighten the cap and leave the water for the full contact time before any is drunk: as a guide, allow the better part of half an hour, longer for cold or cloudy water, because cold slows the chemical and cloudiness shields the organisms. The usual answer for cold or cloudy water is to double the dose and wait longer. The tablets must be dry and within date; tablets gone soft, crumbled, or discoloured may not work at all. Chemical disinfection has one advantage over boiling: it leaves a small protective residual that goes on guarding the water and that, at a water point, can be measured to prove treatment has held.

A short sequence captures the chemical method, the same whether the dose is a tablet, a measured liquid, or a field chlorination ampoule:

   CHEMICAL DISINFECTION  (the steps that make it work)

   1. clear cloudy water first (settle or filter)
   2. add the CORRECT dose for the QUANTITY of water (do not guess)
   3. cap and shake to dissolve and wet the inside
   4. loosen cap, tip and invert: wet the THREADS and lip
   5. tighten and WAIT the full contact time before drinking
        cold or cloudy water -> more dose AND more time

The third is filtration, passing water through a filter to take out suspended matter and, with the right filter, much of the disease. A coarse filter, a clean cloth or a sand-and-charcoal column, clears the mud and improves the taste, but clearing is not cleaning and does not on its own make water safe. A purpose-made filter rated to remove the disease-causing organisms does much more and can make doubtful water genuinely safe, but you must know which kind you hold, because the two look alike in use and only one protects you. Filtration is therefore most useful for clearing cloudy water and is often combined with the others: filter or settle to clear, then boil or disinfect to make safe. This is the warning that governs the whole lesson: clear water is not clean water. Filtering or settling until the water looks clear removes the mud, not the disease.

   MAKING DOUBTFUL WATER SAFE

   choose the best source
        |
        v
   clear it first (let it settle, or filter)   note: clear is NOT clean
        |
        v
   make it safe by ONE of:
        boiling (surest)  .  purification tablets  .  a proper filter
        |
        v
   store it covered and clean, kept apart from untreated water

A caution the practical training drives home: these methods make water safe from disease, not from poison. Water that smells of fuel, oil, or chemicals, or is suspected of any chemical contamination, is not to be treated and drunk at all, because boiling and disinfection do nothing against such hazards and may concentrate them. Set it aside, use a different source, and treat the matter as one for qualified specialists. When in doubt, leave it.

Storing water safely

Treating water is wasted if it is then allowed to become dirty again, and recontamination in storage is one of the commonest ways safe water turns unsafe. Keep treated water in containers that are clean, sound, and covered, with a close-fitting lid or cap so dust, dirt, insects, and dirty hands cannot reach it. Draw it through a tap or a clean dipper kept for the purpose, never by dipping in cups or hands that carry the filth straight back into the supply.

Prepare the container with the same care as the water. Use a kind meant for drinking water, sound and without cracks, cleaned and, if it has held anything doubtful, disinfected before treated water goes in. Never store drinking water in a container that has held fuel, oil, or any chemical, however well rinsed; a can that smells even faintly of fuel is never used for drinking water. Keep it closed except when drawing, and store it out of the sun and off the bare ground so it stays cool and clean. Even treated water does not stay safe for ever: boiled water has no residual and is best used the same day, while chemically treated water holds its residual longer but is still drawn down and refreshed, not left standing for days. Draw through a tap, or with a clean dipper kept solely for the purpose and not set on the ground between uses. Never dip a personal cup, a canteen, or a hand into the stored water: the last few inches between container and cup are where most fouling happens, and a single dirty hand fouls the whole supply at a stroke. This is why a hand-washing place belongs beside the water point.

Above all, keep treated water apart from untreated. Containers for raw or doubtful water must never be used for treated water without being cleaned and disinfected first, and treated-water containers must never be used for anything else. Mark the clean containers plainly and consistently, keep them in their own place apart from the raw-water and washing-water containers, and make the marking a habit so firm that no one stops to wonder which can is which. A single careless filling of a clean can from a dirty one undoes all the treatment at a stroke. The principle runs through all of field sanitation: keep the clean strictly apart from the dirty.

A soldier's water discipline is a single short cycle, repeated faithfully every time: choose the best source, treat it properly, store it clean, and draw it without fouling it. Break any one step and the others are wasted.

   THE WATER CYCLE  (every step, every time)

   CHOOSE  ->  TREAT  ->  STORE  ->  DRAW
   best       boil /     clean,     tap or
   source     tablets /  covered,   clean dipper,
   you can    filter,    marked,    never hands
   reach      full wait  apart      or cups
      ^                                  |
      |__________________________________|
        break one link and the rest is wasted

Safe water at a camp or welfare point

When a camp or relief site must water many people from one supply, the same measures apply on a larger scale, and the stakes are higher, because a single failure now reaches everyone. Protect the supply: guard the source from fouling, place the intake above and away from any contamination, and keep the stored water covered and secure. From it establish one clear, marked treated-water point, where people draw water that is known safe, and only there. Keep raw water, washing water, and waste water well away from the drinking-water point, so the dirty can never reach the clean. A simple hand-washing place beside the water point, and beside the kitchen and the latrines, closes the circle.

Lay the site out so that distance and slope do the guarding for you. Site the latrines, soakage, and washing-water well away from the drinking-water point and, wherever the ground allows, downhill and downstream of it, so nothing drains from the dirty towards the clean. As a working rule, keep latrines and soakage pits a clear distance back from any water source and from the water point, not a pace or two but well back, the same rule Lesson 04 sets out for siting sanitation. Keep the kitchen near the water point but its waste well away from both, and guard the source itself, screening a well-head so animals and feet cannot foul it. The aim is that no one, and no rain shower, can carry filth from where it is made to where the water is drawn.

Bulk water for many people is held in larger containers, fabric drums, collapsible tanks, water cans, or an elevated gravity bag with a tap, and the same rules govern them all, writ larger. Check each before filling for dirt, holes, or any sign it has held fuel or oil; a container that smells of fuel is never used for drinking water. Draw only by tap, never by dipping, and raise a hung gravity bag high enough that its taps are above the reach of animals. Keep a fill hose off the ground or wash its end before use, because a hose mouth dragged through the dirt fouls the whole container it fills. The bulk supply is treated and then watched, not treated once and forgotten.

This is where the chlorine residual earns its keep, and it is worth understanding even at recognition level. When a bulk supply is disinfected with chlorine, the small protective residue left behind can be measured with a simple field test, and that measurement is the proof the water is both safe and staying safe. The practical training teaches the test; what a soldier must grasp is the principle. Water from a proper, approved supply should still show at least a trace of residual at the point where it is drunk, which tells you the protection is holding all the way to the cup. Water the unit has treated up from a raw source is brought to a definite small residual, of the order of a few parts in a million measured after about half an hour, before it is drunk. The residual is then checked before issue and at least once a day after, because chlorine is used up over time and by fresh contamination, so a supply safe yesterday may not be safe today. If the test shows no residual, or too little, the water is treated again before anyone drinks. The lesson is the habit, not the chemistry: at a water point, safe is not decided once, it is kept checking.

For the Army's humanitarian work this is among the most important things a member can do. When a disaster has wrecked the ordinary supply, a stricken population is suddenly without safe water, crowded and weakened, in just the conditions where water-borne disease kills most. A clean, well-run water point can save more lives than almost anything else the Army provides; a careless one can start the very outbreak the relief was meant to prevent. Those most exposed when water fails, the very young, the old, the sick, and the pregnant, are exactly those the relief exists to protect. This work is taught further in Caring for Those in Need and in the Aid to the Civil Power course, but it begins here with water, and it is bound tightly to Lesson 04, on sanitation, because the latrines that protect the water point are the other half of the same job.

A word on how much. A person needs water not only for drinking but for cooking and keeping clean, and the total is more than thirst suggests. As sensible general guidance, plan for several litres a head each day for drinking alone in temperate conditions, and several litres more again for cooking and the washing that hygiene demands. Hard work and heat raise the need sharply: a person labouring in hot weather may need two or three times the drinking water they would need at rest in the cool, and a planner who budgets for the cool will run a working party dangerously short. Cold raises the need too, in a way that surprises people, because thirst is blunted, dry cold air draws water from the breath, and moving over snow is heavy work; under-drinking in the cold is a real danger, covered further in Cold-Weather Operations and Survival. Watch others as well as yourself for the signs of drinking too little: thirst, but more tellingly dark and scanty urine, dry mouth, headache, tiredness and irritability, and falling work and concentration. The plain rule is to drink steadily through the day and not wait for thirst, because people in the field grow short of water before they feel thirsty, and to plan the supply so generously that drinking, cooking, and hygiene are all covered with a margin. The exact figures are settled in the practical training; the principle is that the planned supply must cover drinking, hygiene, and cooking together, with a margin, and must rise for heat, for hard work, and for cold.

In Practice: The Water Point at the Flooded Settlement

A swollen river breaks its banks above a low-lying settlement and drives families to a relief site on higher ground. The Army's first task is water, and one member is made responsible for it. The river runs high and brown, plainly unsafe; there is a hand-pump well at the edge of the site. The member trusts neither on sight. The well is set well back and uphill from where the latrines will go, so it is chosen as the protected source, and its water is disinfected before issue, at the correct dose for the quantity and left for the full contact time. A single clear water point is established under cover, marked plainly, with a tap and a hand-washing place beside it. The cans are checked clean and free of any fuel smell before filling, and the residual is tested before the first issue and again that evening to confirm the treatment is holding. The river water, used only for washing down, is kept at the far side of the camp, its cans marked and never mixed with the drinking cans. People draw drinking and cooking water only from the marked point, and wash their hands there before eating. Downstream, a second family camped on the bank takes its water straight from the river and fouls the ground near it; within days sickness spreads among children already weakened by the flood. At the relief site, where the water was chosen well, treated, tested, and kept clean and separate, no outbreak comes. The flood was the same for both. The difference was the discipline of water.

Check Your Understanding

1. Why is water the first concern of field health, and why does the lesson say contaminated water is so very often the fault of human waste reaching the supply? Trace the chain by which one sick person can poison a whole camp, and name one step in the chain that each of choosing, treating, and storing attacks.
2. Name the three methods of treating doubtful water and say what each does, with its strength and its weakness. Why is boiling called the surest, what are the key steps that make chemical disinfection actually work, and what does the lesson mean by "clear water is not clean water"?
3. Describe how treated water should be stored and drawn, and why the clean must be kept strictly apart from the dirty. At a crowded welfare site, what does the chlorine residual tell you, why is it checked again and again rather than once, and what makes a safe water point so important for the Army's humanitarian work?

Reflection (write a short paragraph): This lesson insists that no field water is safe until treated, however clean it looks, and that a single careless act, a clean can filled from a dirty one, a thread left unwetted, a contact time cut short, or a latrine sited too near the supply, can poison many people at once. Think of a relief or field task where you might be responsible for water. Which step would be easiest to neglect when tired and rushed, and how might that one lapse open the water-borne route of disease for a whole camp, including the vulnerable people you were sent to help?

Summary

• Water is the first concern of field health because everyone must drink, and drink often; water-borne disease, above all diarrhoeal disease, is the commonest field illness, and a single contaminated supply sickens many quickly, very often because human waste has reached it through a chain that loops as the sick become new sources.
• Choose the best source methodically: prefer protected ground water and clear running streams to standing pools, draw upstream of and away from any contamination, check the source and the ground around it, but never trust any source on its appearance.
• Treat all doubtful water by boiling (surest, but leaving no residual), by chemical disinfection with purification tablets at the correct dose, wetting the threads and waiting the full contact time, or by filtration; clear cloudy water first, give cold or cloudy water more dose and more time, and remember that clear water is not clean water and that no treatment makes water safe from fuel or chemical poison.
• Store treated water in clean, covered, sound containers, draw it through a tap or clean dipper and never by hand or dipped cup, and keep treated water strictly apart from untreated, with the safe plainly marked and separated.
• At a camp or welfare point, protect and guard the supply, lay out latrines and washing well away and downhill from the drinking-water point, establish one clear marked treated-water point, treat the bulk supply and then test and watch its chlorine residual before issue and at least daily, and provide for drinking, hygiene, and cooking together with a margin that rises for heat, hard work, and cold; a well-run water point can save more lives at a relief site than almost anything else the Army provides.

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