Water, Is it used wisely?By Aditi Atmasidha

Where does the water go?? Water usage differs greatly from

country to country, depending on how developed a nation is. Other influencing factors include agriculture and supply networks.

The Global Demand of water The amount of water used in the world

every day is very uneven. MEDCs use more water than LEDCs - households, farming and industry all demand water.

Agricultural use of water In MEDCs irrigation is mechanised.

Sprinklers or timed irrigation feeds are used. Where agriculture is common, vast amounts of water can be released at a touch of a button.

In LEDCs irrigation channels are prone to loosing water through evaporation.

Domestic use of water In MEDCs there are a lot of facilities which demand

water use. For example showers, baths, washing machines and swimming pools.

In LEDCs many people do not have access to piped water and so use it more sparingly. Water may be brought to the home from a well or stream.

As a country becomes more wealthy, there will be an increase in its demand for water. Higher levels of industrialisation and more domestic goods such as washing machines all lead to an increase in demand for water. With greater wealth there is also more demand for spas, golf courses and even baths and showers.

Managing water resources One in eight people of the world population do not have access

to safe water. Sixty million children are born each year in LEDCs who do not have access to safe water.

In LEDCs using appropriate technology is usually the best way to manage supply.

Wells, dug by hand, are a common way of accessing water - but the supply can be unreliable and sometimes the well itself can be a source of disease.

Gravity-fed schemes are used where there is a spring on a hillside. The water can be piped from the spring down to the villages.

Boreholes can require more equipment to dig, but can be dug quickly and usually safely. They require a hand or diesel pump to bring the water to the surface.

Managing water reources In addition to locating new sources of water, some strategies

help to reduce the need for water. These include: harvesting (collecting) rainwater landing on buildings recycling waste water to use on crops improving irrigation techniques growing crops less dependant on a high water supply minimising evaporation of water As LEDC cities grow, so does the demand for water. The

problem doesn't end when water supplies have been improved and pipes put in place. The water has got to come from somewhere, and the source of supply may be scarce.

Managing safe water Without safe water people cannot lead healthy and productive

lives. Areas which are in poverty are likely to remain in that way. One example where non-governmental charities have helped break this cycle is in Nigeria.

In Nigeria only 38 per cent of people have access to sanitation. A community led total sanitation project (CLTS) was started by one non-governmental charity. In one year, the project helped 2.5 million people gain access to sanitation. Areas with poor infrastructure, high rates of illness and poverty were identified, and the charity worked with the local population in these areas. The teams worked with the people and educated them as to how poor hygiene and sanitation can make people ill. This included how it can also make others in the community ill. Toilets were built using local, affordable materials. Key people in the community led the work.

By Aditi Atmasidha

Water Treatment

Pure water??????? When we turn our taps on, we naturally

assume the water is safe to drink. This is because it is treated before it is supplied to our homes. In some parts of the country, fluoride is added to the water supply but this is controversial. Water can also be filtered at home – to help improve its taste and quality. In parts of the world where water is more scarce, sea water is distilled to provide drinking water.

Supplying safe water Water is essential for life - it acts as the solvent in

our cells for chemical reactions to take place. Water covers about two-thirds of our planet, but

the vast majority of it cannot be drunk directly. This is because humans need drinking water with low levels of dissolved salts and microbes. To produce water of a sufficient quality, we must:

choose an appropriate source of water filter the water chlorinate the water

Sources of water Sources of water for drinking should be reliable, and

they should also be fresh and free of toxic chemicals (such as heavy metals). In the UK, water resources include lakes, rivers, aquifers and reservoirs.

An aquifer is an underground layer of permeable rock, gravel or sand that is soaked with water, while a reservoir is usually an artificial lake, made by building a dam to accumulate and save river water in the valley behind.

In countries where water is scarce, boreholes are drilled to reach water underground.

Filtering the water Solids in the water, such as leaves and soil, must be

removed. The water is sprayed onto specially-prepared layers of sand and gravel called filter beds.

Different-sized insoluble solids are removed as the water trickles through the filter beds. These are cleaned every so often by pumping clean water backwards through the filter.

The water is then passed into a sedimentation tank. Aluminium sulfate is added to clump tiny particles together to make larger particles, which settle out more easily. The water is then passed through a fine filter, such as carbon granules, to remove very small particles.

The filtration unit

Chlorinating the water Water that has been contaminated with certain

types of microorganisms can be very unsafe. It can cause diseases such as typhoid, cholera and dysentery.

Treating water with chlorine kills microorganisms that may exist in domestic water supplies. Chlorination of water began in the early part of the twentieth century, having a dramatic effect of reducing many waterborne diseases and so increasing public health.

Chlorinating the water There may be disadvantages of consuming

water that has been treated with chlorine. When water is treated with chlorine some disinfection by products called tirhalomethanes (THMs) can form. They form when chlorine reacts with naturally occurring organic matter such as leaves.

There is a notion that THMs can cause cancer, although no firm evidence has been found to support this theory.

Adding fluoride to the water supply Results from scientific research indicate

that fluoridated water can improve dental health by reducing tooth decay. Many areas of the country naturally have low fluoride levels present in the water supply. However, some local health authorities have made water companies add additional fluoride to the water.

Adding fluoride to the water supply Some people argue that extra fluoride

should not be added to water, even if it does improve dental health. They claim that fluoridation:

has been linked to tooth mottling (staining), bone disease and pain

forces people to consume fluoride when they drink tap water - taking away their personal choice (making it unethical)

Filtering water at home Water treatment in the UK means that the water from

your tap is safe to drink. However, the water is not pure because it contains dissolved mineral ions and chlorine.

Some people prefer to filter their water rather than use it straight from the tap. Filtering removes impurities and this can improve the taste and quality of the water. Filtering also helps to soften the water.

Commercially-available systems use cartridges containing water filters. These may be fitted in jugs or kettles, or plumbed in to the home water supply pipework.

Filtering water at home The filter cartridges can contain: silver to kill bacteria carbon (‘activated charcoal’) to absorb impurities, eg

chlorine ion exchange resins to soften the water, and remove

heavy metal ions (such as lead ions) Silver nanoparticles have an antibacterial effect. Their

presence in the filter prevents the growth of bacteria within the filter if water is left inside it for long periods. Silver nanoparticles also help break down harmful pesticides which might be in the water.

Obtaining water from other sources Seawater is a very abundant source of water, but its high salt content

make seawater unsuitable as drinking water. However, pure water can be produced from seawater by distillation.

During distillation, the seawater is boiled. The water vapour is then cooled andcondensed to form pure water - leaving the salt behind.

The disadvantages of producing drinking water this way include: it is expensive because large amounts of energy are needed to heat

the seawater it increases the use of fossil fuels - which are non-renewable resources carbon dioxide emissions from burning fossil fuels contribute to 

global warming Distillation is common in some Middle Eastern countries that have

little rainfall, but are wealthy due to their oil reserves.

Testing water purity The purity of water can be tested by: measuring its boiling point evaporating it (to dryness) on an evaporating

dish Pure water boils at 100°C, but its boiling point

increases as the concentration of dissolved salts increases.

Pure water will leave no solids behind when it is evaporated, whereas impure water will leave solids behind on the evaporating dish.