1. For drinking and for life processes.
On an average, a man consumes about 60,000 to 80,000 litres of water in his lifetime. The body of an adult contains nearly 40 to 50 litres of water at any given time and water constitutes about 66% of the average body make up. Aqueous solutions fill the cells in the body. Nutrients, oxygen, and metabolic waste products are transported by blood, which is mostly water. Digested food is absorbed in the form of an aqueous solution. In plants too nutrients are transported in the form of aqueous solutions.
2. In agriculture
Plants absorb their nutrients from the soil in the form of dilute aqueous solutions. Much of the worlds food crops are now grown under irrigation i.e. where regular water supply is diverted from dams, rivers, lakes etc.
3. In food industry
Water is the common medium used all over the world to prepare various types of foods i.e., for cleaning of food, cooking with/in water: preservation (freezers, fridges etc.) washing and cleaning of utensils, hands etc.
4. In bathing, washing, cleaning, sanitation etc.
5. In industries
Chemical industries are the greatest consumers of water; for instance, 170 litres of water is needed to manufacture just 1 kg of steel and about 144 tons of water is needed to produce one ton of paper.
6. For hydro-electric power production.
7. For transportation as well as recreation.
Transportation by sea and recreation such as swimming, fishing, sailing and other water sports are the important means of using water.
1. For cooking food, for cleaning and drinking.
2. For cultivating food.
3. For transport and recreation.
4. For cleaning.
5. For plants and animals to live in.
6. For factories, industries and power stations
Sources of water:
Sources of fresh water
Main article: Surface water
Lake Chungará and Parinacota volcano in northern Chile Surface water is water in a river, lake or fresh water wetland. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspiration and sub-surface seepage. Although the only natural input to any surface water system is precipitation within its watershed, the total quantity of water in that system at any given time is also dependent on many other factors. These factors include storage capacity in lakes, wetlands and artificial reservoirs, the permeability of the soil beneath these storage bodies, the runoff characteristics of the land in the watershed, the timing of the precipitation and local evaporation rates. All of these factors also affect the proportions of water lost. Human activities can have a large and sometimes devastating impact on these factors. Humans often increase storage capacity by constructing reservoirs and decrease it by draining wetlands. Humans often increase runoff quantities and velocities by paving areas and channelizing stream flow.
The total quantity of water available at any given time is an important consideration. Some human water users have an intermittent need for water. For example, many farms require large quantities of water in the spring, and no water at all in the winter. To supply such a farm with water, a surface water system may require a large storage capacity to collect water throughout the year and release it in a short period of time. Other users have a continuous need for water, such as a power plant that requires water for cooling. To supply such a power plant with water, a surface water system only needs enough storage capacity to fill in when average stream flow is below the power plant’s need. Nevertheless, over the long term the average rate of precipitation within a watershed is the upper bound for average consumption of natural surface water from that watershed.
Natural surface water can be augmented by importing surface water from another watershed through a canal or pipeline. It can also be artificially augmented from any of the other sources listed here, however in practice the quantities are negligible. Humans can also cause surface water to be “lost” (i.e. become unusable) through pollution. Brazil is the country estimated to have the largest supply of fresh water in the world, followed by Russia and Canada.
Under river flow
Throughout the course of the river, the total volume of water transported downstream will often be a combination of the visible free water flow together with a substantial contribution flowing through sub-surface rocks and gravels that underlie the river and its floodplain called the hyporheic zone. For many rivers in large valleys, this unseen component of flow may greatly exceed the visible flow. The hyporheic zone often forms a dynamic interface between surface water and true ground-water receiving water from the ground water when aquifers are fully charged and contributing water to ground-water when ground waters are depleted. This is especially significant in karst areas where pot-holes and underground rivers are common.
Main article: Groundwater
Sub-Surface water travel time
Shipot, a common water source in Ukrainian villages
Sub-surface water, or groundwater, is fresh water located in the pore space of soil and rocks. It is also water that is flowing within aquifers below the water table. Sometimes it is useful to make a distinction between sub-surface water that is closely associated with surface water and deep sub-surface water in an aquifer (sometimes called “fossil water”). Sub-surface water can be thought of in the same terms as surface water: inputs, outputs and storage. The critical difference is that due to its slow rate of turnover, sub-surface water storage is generally much larger compared to inputs than it is for surface water. This difference makes it easy for humans to use sub-surface water unsustainably for a long time without severe consequences. Nevertheless, over the long term the average rate of seepage above a sub-surface water source is the upper bound for average consumption of water from that source.
The natural input to sub-surface water is seepage from surface water. The natural outputs from sub-surface water are springs and seepage to the oceans. If the surface water source is also subject to substantial evaporation, a sub-surface water source may become saline. This situation can occur naturally under endorheic bodies of water, or artificially under irrigated farmland. In coastal areas, human use of a sub-surface water source may cause the direction of seepage to ocean to reverse which can also cause soil salinization. Humans can also cause sub-surface water to be “lost” (i.e. become unusable) through pollution. Humans can increase the input to a sub-surface water source by building reservoirs or detention ponds. Desalination
Main article: Desalination
Desalination is an artificial process by which saline water (generally sea water) is converted to fresh water. The most common desalination processes are distillation and reverse osmosis. Desalination is currently expensive compared to most alternative sources of water, and only a very small fraction of total human use is satisfied by desalination. It is only economically practical for high-valued uses (such as household and industrial uses) in arid areas. The most extensive use is in the Persian Gulf.
An iceberg as seen from Newfoundland
Several schemes have been proposed to make use of icebergs as a water source, however to date this has only been done for novelty purposes. Glacier runoff is considered to be surface water. The Himalayas, which are often called “The Roof of the World”, contain some of the most extensive and rough high altitude areas on Earth as well as the greatest area of glaciers and permafrost outside of the poles. Ten of Asia’s largest rivers flow from there, and more than a billion people’s livelihoods depend on them. To complicate matters, temperatures are rising more rapidly here than the global average. In Nepal the temperature has risen with 0.6 degree over the last decade, whereas the global warming has been around 0.7 over the last hundred years.
Sources Of Water
1. Rainwater. 2. Springs. 3. Rivers and lakes. 4. Surface wells. 5. Deep or artesian wells. Rain water takes up the dust and gases from the air, and organic matter from the roofs over which it is collected. The long storing in a cistern gives bacteria opportunity to grow in large numbers, causing the water to be unsafe for drinking purposes. Springs are a source of pure water supply if they are not contaminated by passing through soil which is polluted. Rivers and lakes are a common source of water supply, but they may be made very unfit for drinking if the surface water and sewage from towns and cities is allowed to drain into them. Surface wells are a very unsafe source of drinking water supply, and the water should never be used when there are cesspools, drains, barnyards, or any other sources of contamination within a radius of 200 feet of them. Deep artesian wells furnish pure water as a rule, unless the piping is not tightly jointed, when impure water from a subsoil stream near the surface may enter the pipes.
Freezing has little effect upon bacteria except to lessen temporarily their vitality. When the ice melts, the bacteria may again become active. Ice made by artificial means from distilled water is the only pure ice. For cooling drinking water, the water should be placed on the ice and the ice should not be put into the water.
Hard And Soft Water
Soft water is water in which no mineral matter is dissolved. Hard water is water in which such minerals as lime, magnesium, and iron are dissolved. Boiling precipitates some of the mineral matter, thus tending to soften the water. This mineral deposit may be seen on the inside of a teakettle. Hard water that is to be used for cleansing purposes may be softened by the addition of washing soda, borax, ammonia, potash, or soda lye.