Facts about water

The most common substance found on earth is water. Water is the only substance found naturally in three forms: solid, liquid and gas.

The amount of water is constant and recycled throughout time; actually, it is possible to drink water that was part of the dinosaur era.
Eighty percent of the earth's surface is water.
Ninety-seven percent of the earth's water is saltwater in oceans and seas. Of the 3% that is freshwater, only 1% is available for drinking - the remaining 2% is frozen in the polar ice caps.
Water serves as nature's thermometer, helping to regulate the earth's temperature.
Water freezes at 32 degrees Fahrenheit, 0 degrees Celsius.
Water boils at 212 degrees Fahrenheit, 100 degrees Celsius.
Once evaporated, a water molecule spends ten days in the air.
Forty trillion gallons of water a day are carried in the atmosphere across the United States.
An acre of corn gives off 4000 gallons of water per day in evaporation.
Forty percent of the atmosphere's moisture falls as precipitation each day.
It would take 1.1 trillion gallons of water to cover one square mile with one foot of water.
One gallon of water weighs 8.34 pounds; one cubic foot contains 7.84 gallons of water.
People need about 2.5 quarts of water a day (from drinking and eating) to maintain good health. A person can live without water for approximately one week, depending upon the conditions.
While usage varies from community to community and person to person, on average, Americans use 183 gallons of water a day for cooking, washing, flushing, and watering purposes. The average family turns on the tap between 70 and 100 times daily.
About 74% of home water usage is in the bathroom, about 21% is for laundry and cleaning, and about 5% is in the kitchen.
A clothes washer uses about 50 gallons of water (the permanent press cycle uses an additional 15 gallons).
It takes 12 to 20 gallons of water to run an automatic dishwasher for one cycle.
About 2 gallons of water are used to brush our teeth.
Flushing a toilet requires 2 to 7 gallons of water.
A 10-minute shower can take 25-50 gallons of water. High flow shower heads spew water out at 6-10 gallons a minute. Low Flow shower heads can cut the rate in half without reducing pressure.
About 25-50 gallons are needed for a tub bath.
A typical garden hose can deliver 50 gallons of water in just 5 minutes.
It takes about four times the amount of water to produce food and fiber than all other uses of water combined.
About 4000 gallons of water are needed to grow one bushel of corn, 11,000 gallons to grow one bushel of wheat, and about 135,000 gallons to grow one ton of alfalfa.
It takes about 1000 gallons of water to grow the wheat to make a two pound loaf of bread, and about 120 gallons to produce one egg.
About 1400 gallons of water are used to produce a meal of a quarter-pound hamburger, an order of fries and a soft drink.
About 48,000 gallons are needed to produce the typical American Thanksgiving dinner for eight people.
About 1800 gallons of water are needed to produce the cotton in a pair of jeans, and 400 gallons to produce the cotton in a shirt.
It takes 39,000 gallons of water to produce the average domestic auto, including tires.
Producing an average-size Sunday newspaper requires about 150 gallons of water.
Water makes up almost two-thirds of the human body, and seventy percent of the brain.
Four hundred gallons of water are recycled through our kidneys each day.
Water makes up 80% of an earthworm, 70% of a chicken, and 70% of an elephant.
Water makes up 90% of a tomato, 80% of pineapples and corn, and 70% of a tree.
About 60,000 public water systems across the United States process 34 billion gallons of water per day for home and commercial use. Eighty-five percent of the population is served by these facilities. The remaining 15 percent rely on 13 million private.
It can take up to 45 minutes for a water supplier to produce one glass of drinking water.
You can refill an 8 oz. glass of water approximately 15,000 times for the same cost as a six pack of soda pop. And, water has no sugar or caffeine.
An average of 800,000 water wells are drilled each year in the United States. That's tapping into our underground water supplies at approximately 100 times each hour for domestic, farming, and commercial needs.
The United States and Canada have about one million miles of pipelines and aqueducts - enough to circle the planet 40 times.

My favourite quotes.

    Water, the Hub of Life.
    Water is its mater and matrix, mother and medium.
    Water is the most extraordinary substance!
    Practically all its properties are anomolous, which enabled life to use it as building
    material for its machinery.
    Life is water dancing to the tune of solids.
        -  Albert Szent-Gyorgyi (1972)

    Water is the driver of Nature.
        - Leonardo da Vinci
        
    We forget that the water cycle and the life cycle are one.
        - Jacques Cousteau

    The crisis of our diminishing water resources is just as severe (if less obviously
    immediate) as any wartime crisis we have ever faced.
    Our survival is just as much at stake as it was at the time of Pearl Harbor, or the Argonne,
    or Gettysburg, or Saratoga.
        -Jim Wright, U.S. Representative, The Coming Water Famine, 1966
        
    High quality water is more than the dream of the conservationists, more than a political
    slogan; high quality water, in the right quantity at the right place at the right time,
    is essential to health, recreation, and economic growth. Of all our planet's
    activities--geological movements, the reproduction and decay of biota, and even the
    disruptive propensities of certain species (elephants and humans come to mind) -- no force
    is greater than the hydrologic cycle.
        - Richard Bangs and Christian Kallen, Rivergods, 1985
    
    Between earth and earth's atmosphere, the amount of water remains constant; there is never
    a drop more, never a drop less.
    This is a story of circular infinity, of a planet birthing itself.
        - Linda Hogan, "Northern Lights," Autumn 1990 

    If you could tomorrow morning make water clean in the world, you would have done, in one
    fell swoop, the best thing you could have done for improving human health by improving
    environmental quality.
        - William C. Clark, speech, Racine, Wisconsin, April 1988
        
    In every glass of water we drink, some of the water has already passed through fishes,
    trees, bacteria, worms in the soil, and many other organisms, including people. . .
    Living systems cleanse water and make it fit, among other things, for human consumption.
        - Elliot A. Norse, in R.J. Hoage, ed., Animal Extinctions, 1985 

    Water is the most critical resource issue of our lifetime and our children's lifetime.
    The health of our waters is the principal measure of how we live on the land."
        -  Luna Leopold

    A river is the report card for its watershed.
        -  Alan Levere

    To put your hands in a river is to feel the chords that bind the earth together."
        -  Barry Lopez 

    When we save a river, we save a major part of an ecosystem, and we save ourselves as well
    because of our dependence--physical, economic, spiritual,--on the water and its community
    of life.
        -  Tim Palmer, - The Wild and Scenic Rivers of America 

    Water is also one of the four elements, the most beautiful of God's creations. It is both
    wet and cold, heavy, and with a tendency to descend, and flows with great readiness.
    It is this the Holy Scripture has in view when it says, "And the darkness was upon the
    face of the deep. And the Spirit of God moved upon the face of the waters."
    Water, then, is the most beautiful element and rich in usefulness, and purifies from all
    filth, and not only from the filth of the body but from that of the soul, if it should
    have received the grace of the Spirit.
        -  John of Damascus (679?-749) Exposition of the Orthodox Faith 

‘Tips for saving water’

There are many effective ways to conserve water in and around your home, apartment, villa, office etc. Following are  simple ways for water conservation.

1. When washing dishes by hand, don’t let the water run while rinsing. Fill one sink with wash water and the other with rinse water.
2. Run your clothes washer and dishwasher only when they are full. You can save up to 1,000 gallons a month.
3. Install covers on pools and spas and check for leaks around your pumps.
4. Monitor your water bill for unusually high use. Your bill and water meter are tools that can help you discover leaks.
5. Encourage your family to keep looking for new ways to conserve water in and around your home.
   
6. Housing Society or Apartment owners association must adopt rainwater harvesting.
7. Turning the water off while you lather the soap can save as many as 5 gallons of water each time you wash. Use one glass of water for brushing teeth instead of running the faucet.
8. In order to reduce the usage of water during toilet flushes, put a One liter bottle filled with water inside each of the flush tanks. This displaces 1-liter volume of water in the tank and thus, saves 1 liter with every full flush.
9. Use dual piping one pipe for drinking, bathing and utensil cleaning where other pipe will bring in rain water and treated water for toilet, lawns etc
10. Use a broom instead of a hose to clean your driveway and sidewalk and save water every time.
11. Shorten your shower by a minute or two and you’ll save up to 150 gallons per month.
12. Teach your children to turn off faucets tightly after each use.
13. A water leak detector or water leak detection system can alert you of any possible plumbing malfunctions in your home or apartment. Even a small leakage can cause huge water losses.
14. Wash your vehicle with bucket of water and sponge than using a hose.
15. Toilet is one of the source wastes water unnecessarily. Upgrade your toilet with new water efficient models.
16. Water your plants deeply but less frequently to encourage deep root growth and drought tolerance.
17. A trained property manager can manage water systems such as saving water in swimming pool, proper management of waste water, detection of leakage etc.
18. The practice of installing individual water meters on multi-family apartment units and billing based on actual consumption results in water savings 8,000 gallons per year.
19. Everyday water is wasted, while bathing and other activities, therefore all new buildings should implement the systems to collect and recycle used water.
20. One must check usage by maids and domestic servants, since it is these people who are the end users of the resource in apartments, villa, office etc.

 
                                      http://www.wateruseitwisely.com/100-ways-to-conserve/index.php

What is National Water Harvesters Network (NWHN)?

National Water Harvesters' Network (NWHN) is a far-reaching network that addresses water issues through people from diverse background in India and abroad. The members of NWHN are primarily professionals, bureaucrats, grassroots functionaries, interested citizens and all those committed in developing or undertaking water harvesting programme. The network addresses and highlights the local issues and the traditional systems relating to water harvesting to further the cause of community based water management.

what is water harvesting ?

It means capturing rain where it falls or capturing the run off in your own village or town. And taking measures to keep that water clean by not allowing polluting activities to take place in the catchment.

Therefore, water harvesting can be undertaken through a variety of ways

• Capturing runoff from rooftops
• Capturing runoff from local catchments
• Capturing seasonal floodwaters from local streams
• Conserving water through watershed management

These techniques can serve the following the following purposes:

• Provide drinking water
• Provide irrigation water
• Increase groundwater recharge
• Reduce stormwater discharges, urban floods and overloading of sewage treatment plants
• Reduce seawater ingress in coastal areas.

In general, water harvesting is the activity of direct collection of rainwater. The rainwater collected can be stored for direct use or can be recharged into the groundwater. Rain is the first form of water that we know in the hydrological cycle, hence is a primary source of water for us. Rivers, lakes and groundwater are all secondary sources of water. In present times, we depend entirely on such secondary sources of water. In the process, it is forgotten that rain is the ultimate source that feeds all these secondary sources and remain ignorant of its value. Water harvesting means to understand the value of rain, and to make optimum use of the rainwater at the place where it falls.

How much water can be harvested?

Urban scenario
The total amount of water that is received in the form of rainfall over an area is called the rainwater endowment of the area. Out of this, the amount that can be effectively harvested is called the water harvesting potential.

Water harvesting potential = Rainfall (mm) x Collection efficiency

The collection efficiency accounts for the fact that all the rainwater falling over an area cannot be effectively harvested, because of evaporation, spillage etc. Factors like runoff coefficient and the first-flush wastage are taken into account when estimated the collection efficiency.
The following is an illustrative theoretical calculation that highlights the enormous potential for water harvesting. The same procedure can be applied to get the potential for any plot of land or rooftop area, using rainfall data for that area..
Consider your own building with a flat terrace area of 100 sq m. Assume the average annual rainfall in your area is approximately 600 mm (24 inches). In simple terms, this means that if the terrace floor is assumed to be impermeable, and all the rain that falls on it is retained without evaporation, then, in one year, there will be rainwater on the terrace floor to a height of 600 mm.

1. Area of plot = 100 sq. m. (120 square yards)
2. Height of the rainfall = 0.6 m (600 mm or 24 inches)
3. Volume of rainfall over the plot = Area of plot x height of rainfall
4. Assuming that only 60 per cent of the total rainfall is effectively harvested
5. Volume of water harvested = 36,000 litres (60,000 litres x 0.6)

This volume is about twice the annual drinking water requirement of a 5-member family. The average daily drinking water requirement per person is 10 litres.
Rural scenario
Community based rainwater harvesting in rural areas of India - the paradigm of the past - has in it as much strength today as it ever did before. It is, in fact, only with this rudimentary technology that people are able to survive in water scarce areas. Recognising this fact, our ancestors had learnt to harvest water in number of ways:

• They harvested the rain drop directly. From rooftops, they collected water and stored it in tanks built in their courtyards. From open community lands, they collected the rain and stored it in artificial wells.
• They harvested monsoon runoff by capturing water from swollen streams during the monsoon season and stored it various forms of water bodies.
• They harvested water from flooded rivers

Assuming that the average Indian population of an Indian village in November 2000 is approximately 1200. India's average rainfall is about 1170 mm. If even only half this water can be captured, though with technology this can be greatly increased, an average Indian village needs 1.12 hectares of land to capture 6.57 million litres of water it will use in a year for cooking and drinking. If there is a drought and rainfall levels dip to half the normal, the land required would rise to a mere 2.24 hectares. The amount of land needed to meet the drinking water needs of an average village will vary from 0.10 hectares in Arunachal Pradesh (average population 236) where villages are small and rainfall high to 8.46 hectares in Delhi where villages are big (average population 4769) and rainfall is low. In Rajasthan, the land required will vary from 1.68-3.64 hectares in different meterological regions and, in Gujarat, it will vary from 1.72-3.30 hectares.  And of course any more water the villagers catch can go for irrigation.
Does this sound like an impossible task? Is there any village that does not have this land availability? India's total land area is over 300 million hectares. Let us assume that India's 587,000 villages can harvest the runoff from 200 million hectares of land, excluding inaccessible forest areas, high mountains and other uninhabited terrains, that still gives every village on average access to 340 hectares or a rainfall endowment of 3.75 billion litres of water. These calculations show the potential of rainwater harvesting is enormous and undeniable.

How water can heal ?

Water has been here, a gift to us since the beginning of time. Many of us take water for granted, never realizing its healing properties, nor honoring its sacredness. We all have heard how we should drink 8 to 10 glasses a day. Some think, that is alot, but if you actually counted how much liquid you do put into you per day, soda, juice, tea, coffee etc., you would find that you really wouldn't have a problem getting down at least that amount if you substituted it with water. Actually it has been proven that we really should drink 2 quarts of water minimum for optimal health.
Not only does water help you to lose weight, by washing out excess fats from your system, but it also helps wash away harmful toxins we consume in the foods we eat.
Lets talk about water therapy. This is something I have found to work in wonderous ways. If you are upset, stressed, or sick, you can stand in a hot shower, and wash your frustrations, sickness or woes away. If you are ill, picture your sickness, the germs and disease or infection, washing down from the top of your head all the way to your toes and down the drain. If you are stressed, stand with your back facing the shower head. Tilt your head back just far enough so that the water is running down right at the top of your forehead line, then slowly move your head foward, letting the water hit the top of your head, then slowly to the back of your head, to the base of your skull, down your neck, to your spinal column, all the way down, slowly, each vertebrae, down to your buttocks, your legs, calves and feet. All of this is done in a slow motion, as the water passes each point, you will feel a tingling, or energy sensation. This sensation is unblocking most of your chakras, releasing tension, balancing and nourishing your body. If you still feel out of whack, repeat again, slowly. Let the water massage you, heal you, nurture you.
Sometimes when you are upset, you cry in the shower, at least I do, its my sanctuary. I let my tears and sadness wash down the drain. By the time my shower is through, my stress is gone, and so is my sadness. Its at this time you can face and logically handle the situation that made you sad. Water has a way of enveloping us into its spirit, like our mothers arms, warm and loving, water caresses us, cradles us within its power.
If you are overweight and trying to lose. Drink water, 2 glasses one half hour before a meal. Its not going to just fill you up and make you eat less, its actually going to help with the digestion of your food. When we don't drink water before our meals, our bodies take the liquid we already had stored inside us, to process our food and we get dehydrated to a point and all backs up. By drinking the water ahead of time it makes for a speedy digestion.
          

The Importance Of Water and Human Health

Water makes up more than two thirds of the weight of the human body, and without it, humans would die in a few days. The human brain is made up of 95% water, blood is 82% and lungs 90%. A mere 2% drop in our body's water supply can trigger signs of dehydration: fuzzy short-term memory, trouble with basic math, and difficulty focusing on smaller print, such as a computer screen. (Are you having trouble reading this? Drink up!) Mild dehydration is also one of the most common causes of daytime fatigue. An estimated seventy-five percent of Americans have mild, chronic dehydration. Pretty scary statistic for a developed country, where water is readily available through the tap or bottle.
Water is important to the mechanics of the human body. The body cannot work without it, just as a car cannot run without gas and oil. In fact, all the cell and organ functions made up in our entire anatomy and physiology depend on water for their functioning.
* Water serves as a lubricant
* Water forms the base for saliva
* Water forms the fluids that surround the joints.
* Water regulates the body temperature, as the cooling and heating is distributed through perspiration.
* Water helps to alleviate constipation by moving food through the intestinal tract and thereby eliminating waste- the best detox agent.
* Regulates metabolism
In addition to the daily maintenance of our bodies, water also plays a key role in the prevention of disease. Drinking eight glasses of water daily can decrease the risk of colon cancer by 45%, bladder cancer by 50% and it can potentially even reduce the risk of breast cancer. And those are just a few examples! As you follow other links on our website, you can read more in depth about how water can aid in the prevention and cure of many types of diseases, ailments and disorders that affect the many systems of our bodies.

What are the Ways to Prevent Water Pollution?

While we need to see to it that the government is stringent about seeing to it that there are adequate treatment plants to treat sewage, and seeing to it that industries have treatment plants and nuclear plants have proper waste storage systems for radioactive material, and so on, there are many things that we can do individually to prevent water pollution. Given below are a few ways to prevent water pollution:

• Toxic products like paints, automobile oil, polishes, and cleaning products should be stored and disposed off properly. As a matter of fact, it is better to use non-toxic, products for the house as far as possible. Also, never dispose off such products by throwing them into your toilet or sink.
• Dispose off your trash in a proper manner and try and incorporate the recycling habit as far as possible. Non-degradable products like tampons, sanitary napkins, and diapers should not be flushed down the toilet, for these can end up damaging the process of sewage treatment, and usually end up as litter on beaches.
• Refrain from throwing litter into streams, lakes, rivers, or seas. If you do spot litter on beaches or in water systems, after ascertaining that it is safe, collect them and dispose off them in any nearby waste disposal system.
• Try using environmentally friendly household products like toiletries, soap-based household cleaning material, and washing powder as far as possible.
• Try using natural fertilizers and pesticides as far as possible, or if not, do not overuse them or over-water gardens and lawns. This will help in reducing the pollutants that get into water systems due to runoffs.
• Automobile oil should be re-used as far as possible. Also, it is important to keep your automobile well maintained in order to prevent leakages of toxic fluids like antifreeze and oil.
• Also, actively conserve water by turning the tap off when you do not need running water, such as while brushing teeth. Apart from preventing water shortages, it lessens the amount of water that needs to be treated.

Effects of Water Pollution

Effects of Run-off Pollution
Rain picks up dirt and silt and carries it into the water. If the dirt and silt settle in the water body, then these sediments prevent sunlight from reaching aquatic plants. If the Sun can't reach the plants, these perish. These sediments also clog fish gills and smother organisms that live on the bottom of the body of the water.

Effects of Oil Pollution and Antifreeze
If oil is spilled on the water, the effects on the ecosystem and the components are harmful. Many animals can be annihilated in case they ingest oil. Oil contaminated prey may be a reason of death for many. If the oil coats the feathers of birds, these may die. Oil and antifreeze makes the water have a foul odor and there is a sticky film on the surface of water that kills animals. Oil is the most harmful pollutant in the water.

Contaminated Ground Water Effects
If contaminated water enters the ground, there may be serious effects. People may become very sick and there is a probability of developing liver or kidney problems and cancer or other illnesses.

Fertilizers and other chemicals
Nitrates in drinking water leads to diseases of infants that may lead to their death. Cadmium is a metal in sludge-derived fertilizer. This can be absorbed by crops. When people ingest this, they may cause diarrheal disorders, liver and kidney damage. The inorganic substances like mercury, arsenic and lead are the causes of pollution. Other chemicals can also lead to problems concerning the taste, smell and color of water. Pesticides, PCBs and PCPs are all poisonous to all sorts of life. Pesticides are used in farming, homes and forestry. PCBs are found as insulators in old electrical transformers. PCPs are found in products like wood preservatives.

Effects of Agricultural Water Pollution
Rain and irrigation water drains off cultivated land that has been fertilized and treated with pesticides, the excess nitrogen and poisons are mixed with it into the water supply. These pesticides are toxic and pollute the water in a different mode. Aquatic plants growth cause de-oxygenation of water and annihilate flora and fauna in a stream, lake and river. Fertilizers enhance the growth of bacteria that are in water and increase the concentration of bacteria to hazardous levels.

Effects of Thermal Water Pollution
Machinery in the industries are cooled with water from lakes and rivers. This water reaches the river in a heated state. This water decreases the ability of the aquatic system to hold oxygen and raises the growth of warm water species.

Effects of Heavy Metal Water Pollution
Heavy metals like lead, mercury, iron, cadmium, aluminum and magnesium are present in water sources. If these metals are present in the sediment, these reach the food chain through plants and aquatic animals. This causes heavy metal poisoning in case the level in the water is very high.

Some other effects of water pollution
In rivers, oceans and seas, water pollution effects flora and fauna in them. Further, the birds and animals that consume this contaminated food supply can perish. Blood diseases, nervous system disorders and heart diseases are some of the effects of water pollution. Many toxins in polluted water lead to cancer. Rarely, the body's chromosomal makeup can be altered. Some of the less potent effects are skin lesions, vomiting and diarrhea.

Causes of Water Pollution

The causes of water pollution may be due to direct and indirect contaminant sources. The former are effluent outputs from refineries, factories, waste treatment plants. Fluids of differing qualities are emitted to the urban water supplies. In the United States and some other countries, these methods are controlled. However, still pollutants can be found in the water bodies. The latter are the water supply from soils/groundwater systems that have fertilizers, pesticides and industrial wastes. Also those through the atmosphere like bakeries, factories emission and automobile discharge. Contaminants can also be divided into inorganic, organic, acid/base and radioactive.

Organic water pollutants are:

• Food processing waste, including pathogens
• Insecticides and herbicides, a huge range of organohalide and other chemicals
• Tree and brush debris from logging operations
• Bacteria from sewage or livestock operations
• Petroleum hydrocarbons like diesel, gasoline, jet fuels, fuel oils, motor oils
• Volatile organic compounds like industrial solvents

Inorganic water pollutants are:

• pre-production industrial raw resin pellets
• heavy metals including acid mine drainage
• chemical waste as industrial by-products
• acidity due to industrial discharges like sulphur dioxide
• silt in surface runoff due to logging, slash and burn practices, construction sites or land clearing sites
• fertilizers in runoff from agriculture including nitrates and phosphates

Causes of water pollution

The major sources of water pollution are as described below. Discharge of contaminated and/or heated water that has been used for industrial purposes. The surface runoff that contains spilled petroleum products. The surface runoff from farms, construction sites or other impervious surfaces. The improper disposal of solid wastes like littering on a localized scale. Addition of excessive nutrients by runoff containing detergents or fertilizers called as eutrophication. The geology of aquifers where groundwater is abstracted. Maltreated sewage discharged in a wrong manner. Slash and burn farming practice is a component in shifting cultivation agricultural systems. Radioactive substances from nuclear power plants and industrial, medical and scientific use are also contributive. Uranium and thorium mining and refining are some of the examples. Heat is a leading cause as it results in the death of several aquatic organisms. A discharge of cooling water by factories and power plants lowers the temperature of the water bodies. Oil pollution is very harmful for coastal wildlife. Oil spreads on huge areas to form oil slicks. If there are trials to sink the oil or chemically treat it, the marine and beach ecosystems may be further disrupted.

Classification of the causes of water pollution

Municipal, industrial and agricultural are the different categories of the causes of water pollution. Municipal causes are related to waste water from homes and commercial establishments. The main aim of handling municipal wastewater was to decrease the harmful bacteria, oxygen requiring materials, mixed inorganic compounds and suspended solids. Industrial causes vary as per the biochemical demand, suspended solids, inorganic and organic substances. Agricultural causes include commercial livestock and poultry farming. These lead to organic and inorganic pollutants in surface waters and groundwater.

Other agents

• The combustion of coal leads to the release of mercury in the atmosphere. This enters the rivers, lakes and groundwater. This is very hazardous for pregnant women and infants.
• Cattle and pig rearing causes a significant amount of nutrient-filled waste. Virulent pfiesteria toxin collects in the water masses.
• Fertilizers having a large quantity of nitrogen and phosphorus cause a high biological oxygen demand in the water. As oxygen is depleted, only anaerobic life-forms prosper.
• Human settlement along the banks of rivers causes human, animal and industrial waste to be discharged into it. In the developed world, sewage treatment plants are used to treat waste. However, in developing nations, the rivers are similar to open sewers.

How do we know if our water is polluted?

If your water is treated by your local Water Authority, then they will certify if it is fit for drinking (potable) or not. If there is some local contamination, then they should notify you of what to do. It is common in cases of flood and earthquake where water has become polluted that people are warned to boil water before drinking.

If you get your water from a well or other source like a stream or river, then it is difficult to know how clean it is. If the water is from a small stream high in the mountains and you know there are no factories or dead animals further up the mountain, then you can drink the water safely. Few people are in that fortunate situation.

If there is any doubt, then boil the water with a rapid bubbling for at least two minutes before using. (There are various other ways of doing this. One is using sunlight for several hours on water in plastic bottles.) This will kill any live organisms that can cause diarrhoea and other nasty tummy bugs. But it will not remove heavy metals and other pollutants.

You may also be able to send a sample away for analysis.

Types of water pollution

Water pollution can come from a number of different sources. If the pollution comes from a single source, such as an oil spill, it is called point-source pollution. If the pollution comes from many sources, it is called nonpoint-source pollution.
Most types of pollution affect the immediate area surrounding the source. Sometimes the pollution may affect the environment hundreds of miles away from the source, such as nuclear waste, this is called transboundary pollution.

What is Water pollution ?

Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans and groundwater). Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds.

Emergency Water Filtration Methods

Always filter water as a first step in emergency water treatment. When municipal water supplies falter and electrical power fails, homeowners must turn to unusual sources. Serious illness could result from drinking without filtering and treating available water from plumbing reservoirs, swimming pools and waterways. Homemade filters and commercial filters help avoid these problems.

Crude Filters

1. Boiling or chemically treating water will actually be the real defense against water-borne disease, but filtration helps by removing many contaminants. If the water is cloudy, let it settle and filter it through layers of clean cloth. Boiling the water for one minute meets government standards for safe drinking, but other experts recommend boiling for ten. Five to eight drops of chlorine bleach per gallon of water will also kill harmful bacteria and viruses. Crude filters only remove obvious debris.

Ceramic Filters

2. Ceramic water filters that remove particles down to one micron in diameter effectively remove harmful organisms and provide immediately drinkable water. Not all filters sold for improving the quality of tap water meet these standards. Check with the manufacturer to find out what additional steps may be needed. Filters that depend upon a pressurized water system to operate won't be of help in a real emergency.

Homemade Filters

3. Homemade water filters built in stages filter water in large amounts but not perfectly. The filter stages should run from coarse to fine--first stages screen out large pieces of debris and later stages remove finer particles. If the last stage is a deep layer of activated charcoal, like that used in aquarium water filters, the result will be water that looks clean. Disinfect it by boiling or treatment with chemicals before drinking it. Layered filters in clean 50 gallon drums can process rainwater from a gutter system for storage in tanks or cisterns. Rooftops catch more than rain--runoff may include grit and asphalt residue from shingles, bird droppings and dead insects. Gutters may conceal dead animals. Homemade filters are not enough to guarantee potable water.

Backpacking Filters

4. Though their total output can be as low as 200 gallons per filter, small backpacking water filters are a great idea for the home emergency kit as well as for a camping vacation. Combined with simple cloth filters to remove coarse debris, backpacking filters produce drinkable water from emergency sources like hot water heaters and even the reservoirs of toilets.

Survival Filters

5. Emergencies don't only happen in the cities--in a wilderness situation when clean water runs short, an emergency filter pit dug in the bank of a creek or the shore of a lake uses the ground itself as a primitive filter. Wait for the hole to fill and the water to clear before filling a container. Stage filters with found materials like dry grass or clean sand can be rigged from spare clothing.

How do specific water purification methods work?

1 Physical water purification

Physical water purification is primarily concerned with filtration techniques. Filtration is a purification instrument to remove solids from liquids. There are several different filtration techniques. A typical filter consists of a tank, the filter media and a controller to enable backflow.

Screens
Filtration through screens is usually done at the beginning of the water purification process. The shape of the screens depends on the particles that have to be removed.

Sand filtration
Sand filtration is a frequently used, very robust method to remove suspended solids from water. The filter medium consists of a multiple layer of sand with a variety in size and specific gravity. When water flows through the filter, the suspended solids precipitate in the sand layers as residue and the water, which is reduced in suspended solids, flows out of the filter. When the filters are loaded with particles the flow-direction is reversed, in order to regenerate it. Smaller suspended solids have the ability to pass through a sand filter, so that secondary filtration is often required.

Cross flow filtration
Cross flow membrane filtration removes both salts and dissolved organic matter, using a permeable membrane that only permeates the contaminants. The remaining concentrate flows along across the membrane and out of the system and the permeate is removed as it flows along the other side of the membrane.
There are several different membrane filtration techniques, these are: micro filtration, ultra filtration, nano filtration and Reversed Osmosis (RO). Which one of these techniques is implemented depends upon the kind of compounds that needs to be removed and their particle size. Below, the techniques of membrane filtration are clarified.
1) Microfiltration
Microfiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of 0.1 to 1.5 microns, are separated from a liquid. It is capable of removing suspended solids, bacteria or other impurities. Microfiltration membranes have a nominal pore size of 0.2 microns.
2) Ultrafiltration
Ultrafiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of 0.005 to 0.1 microns, are separated from a liquid. It is capable of removing salts, proteins and other impurities within its range. Ultrafiltration membranes have a nominal pore size of 0.0025 to 0.1 microns.

3) Nanofiltration
Nanofiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of approximately
0.0001 to 0.005 microns, are separated from a liquid. It is capable of removing viruses, pesticides and herbicides.

4) Reversed Osmosis (RO)
Reversed Osmosis, or RO, is the finest available membrane separation technique. RO separates very fine particles or other suspended matters, with a particle size up to
0.001 microns, from a liquid. It is capable of removing metal ions and fully removing aqueous salts.
More on RO

Cartridge filtration
Cartridge filtration units consist of fibres. They generally operate most effectively and economically on applications having contamination levels of less than 100 ppm. For heavier contamination applications, cartridges are normally used as final polishing filters.

2 Chemical water purification

Chemical water purification is concerned with a lot of different methods. Which methods are applied depends on the kind of contamination in the (waste)water. Below, many of these chemical purification techniques are summed up.

Chemical addition
There are various situations in which chemicals are added, for instance to prevent the formation of certain reaction products. Below, a few of these additions are summed up:
- Chelating agents are often added to water, in order to prevent negative effects of hardness, caused by the deposition of calcium and magnesium.
- Oxidizing agents are added to act as a biocide, or to neutralize reducing agents.
- Reducing agents are added to neutralize oxidizing agents, such as ozone and chlorine. They also help prevent the degradation of purification membranes.

Clarification
Clarification is a multi-step process to remove suspended solids. First, coagulants are added. Coagulants reduce the charges of ions, so that they will accumulate into larger particles called flocs. The flocs then settle by gravity in settling tanks or are removed as the water flows through a gravity filter. Particles larger than 25 microns are effectively removed by clarification. Water that is treated through clarification may still contain some suspended solids and therefore needs further treatment.

Deionisation and softening
Deionisation is commonly processed through ion exchange. Ion exchange systems consist of a tank with small beds of synthetic resin, which is treated to selectively absorb certain cations or anions and replace them by counter-ions. The process of ion exchange lasts, until all available spaces are filled up with ions. The ion-exchanging device than has to be regenerated by suitable chemicals.
One of the most commonly used ion exchangers is a water softener. This device removes calcium and magnesium ions from hard water, by replacing them with other positively charged ions, such as sodium.
Disinfection Disinfection is one of the most important steps in the purification of water from cities and communities. It serves the purpose of killing the present undesired microrganisms in the water; therefore disinfectants are often referred to as biocides. There are a variety of techniques available to disinfect fluids and surfaces, such as: ozone disinfection, chlorine disinfection and UV disinfection.
Chlorine has a downside: it can react to chloramines and chlorinated hydrocarbons, which are dangerous carcinogens. To prevent this problem chlorine dioxide can be applied. Chlorine dioxide is an effective biocide at concentrations as low as
0.1 ppm and over a wide pH range. ClO₂ penetrates the bacteria cell wall and reacts with vital amino acids in the cytoplasm of the cell to kill the organism. The by-product of this reaction is chlorite. Toxicological studies have shown that the chlorine dioxide disinfection by-product, chlorite, poses no significant adverse risk to human health.
Ozone has been used for disinfection of drinking water in the municipal water industry in Europe for over a hundred years and is used by a large number of water companies, where ozone generator capacities up to the range of a hundred kilograms per hour are common. When ozone faces odours, bacteria or viruses, the extra atom of oxygen destroys them completely by oxidation. During this process the extra atom of oxygen is destroyed and there are no odours, bacteria or extra atoms left. Ozone is not only an effective disinfectant, it is also particularly safe to use.
UV-radiation is also used for disinfection nowadays. When exposed to sunlight, germs are killed and bacteria and fungi are prevented from spreading. This natural disinfection process can be utilised most effectively by applying UV radiation in a controlled way.

Distillation
Distillation is the collection of water vapour, after boiling the wastewater. With a properly designed system removal of organic and inorganic contaminants and biological impurities can be obtained, because most contaminants do not vaporize. Water will than pass to the condensate and the contaminants will remain in the evaporation unit.

Electro dialysis
Electro dialysis is a technique that employs an electrical current and special membranes, which are semi permeable to ions, based on their charge. Membranes that permeate cations and membranes that permeate anions are placed alternately, with flow channels between them, and electrodes are placed on each side of the membranes. The electrodes draw their counter ions through the membranes, so that these are removed from the water.

pH-adjustment
Municipal water is often pH-adjusted, in order to prevent corrosion from pipes and to prevent dissolution of lead into water supplies. The pH is brought up or down through addition of hydrogen chloride, in case of a basic liquid, or natrium hydroxide, in case of an acidic liquid. The pH will be converted to approximately 7 to 7.5, after addition of certain concentrations of these substances.

Scavenging

Most naturally occurring organics have a slightly negative charge. Organic scavenging is done by addition of strong-base anion resin. The organics will fill up the resin and when it is loaded it is regenerated with high concentrations of sodium chloride.

3 Biological water purification

Biological water purification is performed to lower the organic load of dissolved organic compounds. Microrganisms, mainly bacteria, do the decomposition of these compounds. There are two main categories of biological treatment: aerobic treatment and anaerobic treatment.
The Biological Oxygen Demand (BOD) defines the organic load. In aerobic systems the water is aerated with compressed air (in some cases merely oxygen), whereas anaerobic systems run under oxygen free conditions.

What specific water purification methods are there?

Water that is distributed in cities or communities is treated extensively. Specific water purification steps are taken, in order to make the water meet current water standards.
Purification methods can be divided up into settling of suspended matter, physical/ chemical treatment of colloids and biological treatment. All these treatment methods have several different applications.

Water and wastewater purification

Rain water collected from storm drains is purified with reverse osmosis water processors and used for landscape irrigation and industrial cooling in Los Angeles and other cities, as a solution to the problem of water shortages.
In industry, reverse osmosis removes minerals from boiler water at power plants. The water is boiled and condensed repeatedly. It must be as pure as possible so that it does not leave deposits on the machinery or cause corrosion. The deposits inside or outside the boiler tubes may result in under-performance of the boiler, bringing down its efficiency and resulting in poor steam production, hence poor power production at turbine.
It is also used to clean effluent and brackish groundwater. The effluent in larger volumes (more than 500 cu. meter per day) should be treated in an effluent treatment plant first, and then the clear effluent is subjected to reverse osmosis system. Treatment cost is reduced significantly and membrane life of the RO system is increased.
The process of reverse osmosis can be used for the production of deionized water.
RO process for water purification does not require thermal energy. Flow through RO system can be regulated by high pressure pump. The recovery of purified water depend upon various factor including - membrane sizes, membrane pore size, temperature, operating pressure and membrane surface area.
In 2002, Singapore announced that a process named NEWater would be a significant part of its future water plans. It involves using reverse osmosis to treat domestic wastewater before discharging the NEWater back into the reservoirs.

Sewage treatment

Sewage treatment is the process that removes the majority of the contaminants from wastewater or sewage and produces both a liquid effluent suitable for disposal to the natural environment and a sludge. To be effective, sewage must be conveyed to a treatment plant by appropriate pipes and infrastructure and the process itself must be subject to regulation and controls. Some wastewaters require different and sometimes specialized treatment methods. At the simplest level, treatment of sewage and most wastewaters is carried out through separation of solids from liquids, usually by sedimentation. By progressively converting dissolved material into solids, usually a biological floc which is then settled out, an effluent stream of increasing purity is produced.

Processes for drinking water

A combination selected from the following processes is used for municipal drinking water treatment worldwide:

• Pre-chlorination - for algae control and arresting any biological growth
• Aeration - along with pre-chlorination for removal of dissolved iron and manganese
• Coagulation - for flocculation
• Coagulant aids, also known as polyelectrolytes - to improve coagulation and for thicker floc formation
• Sedimentation - for solids separation, that is, removal of suspended solids trapped in the floc
• Filtration - removing particles from water
• Desalination - Process of removing salt from the water
• Disinfection - for killing bacteria.

There is no unique solution (selection of processes) for any type of water. Also, it is difficult to standardise the solution in the form of processes for water from different sources. Treatability studies for each source of water in different seasons need to be carried out to arrive at most appropriate processes.
The above mentioned technologies are well developed and generalised designs are available which are used by many water utilities (public or private). In addition to the generalised solutions, a number of private companies provide solutions by patenting their technologies.

Potable water purification

Water purification is the removal of contaminants from untreated water to produce drinking water that is pure enough for the most critical of its intended uses, usually for human consumption. Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, minerals such as iron, manganese and sulphur, and other chemical pollutants such as fertilisers.
Measures taken to ensure water quality not only relate to the treatment of the water, but to its conveyance and distribution after treatment as well. It is therefore common practice to have residual disinfectants in the treated water in order to kill any bacteriological contamination during distribution.
World Health Organisation (WHO) guidelines are generally followed throughout the world for drinking water quality requirements. In addition of the WHO guidelines, each country or territory or water supply body can have their own guidelines in order for consumers to have access to safe drinking water.

Water treatment

Water treatment describes those processes used to make water more acceptable for a desired end-use. These can include use as drinking water, industrial processes, medical and many other uses. The goal of all water treatment process is to remove existing contaminants in the water, or reduce the concentration of such contaminants so the water becomes fit for its desired end-use. One such use is returning water that has been used back into the natural environment without adverse ecological impact.

The processes involved in treating water for drinking purpose may be solids separation using physical processes such as settling and filtration, and chemical processes such as disinfection and coagulation. Biological processes are also employed in the treatment of wastewater and these processes may include, for example, aerated lagoons, activated sludge or slow sand filters.