SAFE DRINKING WATER
DR. S.M. ALAM
Mar 28 - Apr 3, 2011
Water is a chemical substance with the chemical formula H2O. Its molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on earth with its solid state, ice, and gaseous state, water vapor or steam.
Drinking water is one of the human body's primary and basic need, so much so that a man can go on living for up to 50 days or more without food, but it will be almost impossible for him to live, if he is not given water for more than two days.
Water covers 70.9 per cent of the Earth's surface and is vital for all known forms of life.
On earth, it is found mostly in oceans and other large water bodies, with 1.6 per cent of water below ground in aquifers and 0.001 per cent in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Oceans hold 97 per cent of surface water, glaciers and polar ice caps 2.4 per cent, and other land surface water such as rivers, lakes, and ponds 0.6 per cent. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Water on earth moves continually through a cycle of evaporation or transpiration (evapo-transpiration), precipitation, usually reaching to the oceans. Evaporation and transpiration contribute to the precipitation in form of rain on the land.
Water is primary and basic need. It is a well documented fact that the universe is composed of 29 per cent land and 71 per cent of water. Water is the earth's most distinctive constituent, natural resource and is essential ingredient, and premium of life. It is among the most essential requisites that nature provides to sustain life of plants, animals, and humans. The uses of water are numerous and life without water is impossible. A constant supply of clean and healthy water is most essential for all citizens of the country. However, a shortage of fresh water is probably going to be most serious resource problem, the burgeoning population anywhere of the planet will face, in the next coming years. As with human food, this problem is not one of global shortage, but one of uneven distribution. Water associated with land and is held in the polar icecaps and big glaciers of the world and about 25 per cent is found in groundwater and much uneconomical of which is for use. This scenario leaves only a small percentage of readily manageable fresh water as a source of the water supply, where water is plentiful, people are frequently a few and vice-versa.
The country Iceland in Europe is the most water-rich country but most water poor country is Egypt in Africa. Most of the water in the hydrosphere is salty and much of the fresh water is frozen. It has been estimated that vast oceans all over the world contain about 97 per cent of the planet's water. Seven continents contain about 2.8 per cent and the atmosphere about 0.001 per cent.
In Pakistan, the drinking water supplies are sourced from rivers, canals, lakes and underground water aquifers. The quality of this water is suspect because of poor municipal and sewerage management, the dumping of untreated effluents and inadequate water treatment facilities. Surveys and water quality studies conducted by organizations such as WHO, the Pakistan Council for Research on Water Resources and WWF Pakistan indicate that our water supplies contain different concentrations of arsenic, pesticide and nitrate among other chemicals that are dangerous to human health.
Clean drinking water is essential to humans and other life forms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. A recent report suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50 per cent.
Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation.
Water is among the most essential requisites that nature provides to sustain life of plants, animals, and humans. The total quantity of fresh water on earth can satisfy all the needs of human population if it is evenly distributed and becomes accessible to all. However, the fact is that water is not evenly distributed or accessible to large sections of global population. This defines the central resource management problem.
Water is a substance of paramount ecological, economic and social importance. It is the essence of life and a constant supply of clean, healthy water is essential for all citizens of the country. It is the most important element in the figurative pipeline of life and with more than 80 per cent of every living thing (from human body to a lonely plant in a desert) on planet earth will, rather literally wither away without water. Water acts as a carrier, supplying nutrients to our cells and delivering waste products to our excretory organs. The human body contains anywhere from 55 to 78 per cent water. Infants have the highest and the elderly the lowest amount of water in their tissue. To function properly, the body requires between one and seven liters of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors. Most of this is ingested through foods or beverages other than drinking straight water. It is not clear how much water intake is needed by healthy people, though most advocates agree that 8 glasses of water daily is the minimum to maintain proper hydration. Medical literature favors a lower consumption, typically 1 liter of water for an average male, excluding extra requirements due to fluid loss from exercise or warm weather. For those who have healthy kidneys, it is rather difficult to drink too much water, but (especially in warm humid weather and while exercising) it is dangerous to drink too little. People can drink far more water than necessary while exercising, however, putting them at risk of water intoxication, which can be fatal. Common impurities include metal salts and oxides (including copper, iron, calcium, lead, arsenic, mercury, cadmium, nickel, cobalt etc.) and/or harmful bacteria, such as vibrio. Some solutes are acceptable and even desirable for taste enhancement and to provide needed electrolytes.
Safe drinking water is essential for good health and is a prerequisite to the control of diseases most commons in developing countries. One of the main objectives of management of water is to provide safe water to people in adequate quantities for drinking, food preparation, and personal hygiene at a low cost keeping in view the economic level of the community. Disposal of wastewater creates another problem. In humid area, pools of such water breed mosquitoes and in case of open drains, human and animal wastes can contaminate the groundwater, which can be protected by proper and effective management of water resources.
The criteria for drinking water are different from those as fixed for crops. The World Health Organization (WHO) has fixed certain standards. The US Public Health Services Standards are also very similar to those of the WHO. The total dissolved solids (TDS) being considered desirable for drinking purpose are 500 mg/l, and those permitted are 1000 mg/l. The recommended permissible limits and in some cases considered necessary are presented below (mg/l).
A drinking water must be safe to drink, pleasant to taste and usable for domestic purposes. Polluted or contaminated water contains microorganisms.
Some bacteria (such as Salmonella, Pseudomonas etc.) and many other harmful microorganisms are found in water. Some are harmless and other cause diseases such as typhoid fever, meningitis is, bloody diarrhea, dysentery, cholera, food poisoning, urinary tract infections, gastrointestinal diseases, vomiting, serve headache and muscular abdominal cramps, etc. One type of bacteria grows in iron bearing water and help in precipitating iron oxide or rot.
For safe drinking and maintaining the general health, the water should be boiled for at least 25 minutes because boiling removes germ: boiled water should be filtered before drinking and covered while cooling containers for storing water must be cleaned each time before filling. Always avoid the use of bottled water from the markets as it is environmentally unfriendly, expensive, creates a mindset of apathy and reduces the pressure on the state to improve water management and provisioning services. According to WHO standards, one pound of chlorine should be used for one million gallon of potable water in normal season, while its quality should almost be doubled in the rainy season.
CONCLUSION: Water is one of the most fundamental of natural resources that a country must harness in its efforts for rapid economic development. The roll of water in the development process cannot be overemphasized. The demand for water in the country has increased tremendously over the years and will continue to increase in view of the accelerating pace of population growth, urbanization, and industrialization. Comprehensive water resource management is necessary for the benefit of citizens in the country.