There is evidence of widespread contamination of water resources in many areas of our country. The Environmental Protection Agency's National Water Quality Inventory of 1994 has identified agriculture, urban runoff/storm water, and municipal point sources as the largest pollutant sources for rivers, lakes, and estuaries. Contaminants from these sources include pesticides, metals, nitrates, solvents, and other wastes. More than 200 chemical constituents have been documented in groundwater alone. The health effects of long term exposure to many of the contaminants entering our water supply are unknown. But it should be noted that not all contamination events pose a threat to our health. The National Water Quality Inventory 1994 Report to Congress states that 40% of flowing river and stream miles can be used for drinking water after conventional water treatment, and 37% of lake and reservoir acres meet the designated use criteria for drinking water.

Pollutant concentrations become diluted when they enter water sources and are further reduced by biological degradation, filtration, and adsorption to soil. Some chemicals, such as the man-made chlorinated hydrocarbons, are very stable in the environment. Some of these compounds accumulate in living organisms and are not readily metabolized and excreted.

The impacts of contamination events to lakes and reservoirs are more severe and persistent than streams and rivers because there is not a natural flushing process as is characterized by the flow in streams and rivers.Contamination is even more persistent in groundwater due to lack of biological degradation. The most biologically active bacteria live within the soil above groundwater supplies.

In contrast to surface water there is not a lot of mixing when a contaminant enters groundwater. When a contaminant first enters the soil it will travel down vertically with gravity until contact with groundwater. At this point it will begin to flow primarily in a horizontal direction. The contaminant will then spread out three-dimensionally like smoke from a chimney and is called a plume. Groundwater does not exhibit turbulent flows as found in surface water. The flow is defined by gravity, pressure and friction. It is much more constant than surface water. An aquifer can flow at a fraction of an inch per day up to a few feet per day.

Have you ever given a second thought as to whether the water you are drinking is pure? Of the 8 glasses of water that you drink every day, do you actually know how many harmful germs you are taking in? Water purification systems in our homes usually do a good job of filtering water and making it safe for drinking, but why then do we still fall prey to food poisoning, typhoid and dysentery? To understand this, it’s important to uncover the basics first. Read on to know more about what pure water actually implies, the popular and common contaminants of water and their sources, and how these contaminants can greatly impact your health.

Pure water: Water that is free from all materials and substances that may make it toxic to human life and unfit for consumption is termed as pure water. Innumerable deaths are caused every year due to lack of clean drinking water facilities in the country.

Common contaminants and their sources: The most common source of contaminated water is toxic matter from industries and factories, which is discarded into drinking water bodies. Leakages in sewer lines, septic tanks, raw sewage overflow and dumping of waste into water bodies is yet another reason of contamination.

Nitrates, toxic minerals, salts, micro-organisms like e.coli, giardia, helminthes and cryptosporidium are some common contaminates which claim many lives every year. Another sad truth of the state of water safety in India is that despite the presence of advanced systems of water purification, many still fall prey to such illnesses. This is mostly because many a times, faults and improper functioning of the purification systems go unnoticed and ignored.

Health issues caused due to intake of contaminated water: A large percentage of deaths occurring today due to diarrhoea are mostly observed in children under the age of 5 years, and this is most commonly observed in developing countries. Improper sanitation is a major problem, and should be resolved at the earliest.

Intake of contaminated water can lead to several health problems, some of which are listed below:

Diarrhoea: Diarrhoea is one of the most common health issues that can occur as a result of drinking water contamination. Though diarrhoea is not a grave disease, if ignored, it can prove to be fatal. Vomiting, nausea, severe dehydration are all common symptoms of diarrhoea.

Typhoid: Caused due to the bacterium salmonella typhi, typhoid is yet another health issue that can occur after intake of contaminated water. Clinical and lab reports confirm the presence of typhoid bacteria, after which treatment measures should be taken immediately.

Chronic health conditions: Toxic minerals taken in through contaminated water though do not show their harmful effects immediately, but in the long run, they can build up and cause a huge, sometimes permanent damage to the body. Chronic health effects like liver and kidney damage, cancer, birth defects and permanent damage to the immune and nervous system can also occur due to contaminated water.

Acute health effects: High levels of contaminants can often cause severe health problems, almost immediately. Skin rashes, nausea, vomiting, dizziness and lung irritation are a few examples.

We take the safety of our water for granted, but accidents occur every year in which water unfit for human consumption is supplied to thousands of households. Concerns have been raised about pesticides and gender-bending chemicals in the water supply, and traces of hundreds of substances can be found in tap water. Excess amounts can damage our health and the effects of many remain undiscovered.

What is really in our water, and how can we make sure it is as safe as possible?

CHLORINE: Liquid chlorine is added during water treatment to kill bacteria, though the cryptosporidium strain - the cause of amoebic dysentery - and parasites such as giardia are extremely resistant to it. Although many people do not like the taste and smell of chlorine, water companies insist that it is safer than dechlorinated water which is left sitting out at room temperature. Activated carbon filters, found in basic jug-type filters as well as more sophisticated systems, remove chlorine. Chlorine will also evaporate off by itself in about half an hour if left in an open container like a glass or a jug.

ORGANISMS: The bacteria M. Avium paratuberculosis (MAP), a cousin of the tuberculosis germ, is found in farm animals in which it causes chronic intestinal inflammation. This microscopic organism is believed by some experts to be a cause of Crohn's disease, the debilitating human gut disorder. Cryptosporidium, another parasite resistant to chlorination, occasionally causes outbreaks of gastrointestinal illness - potentially fatal for the old or those with a weak immune system. But Cryptosporidium can be removed from water with ceramic filters and distillation systems.

PESTICIDES, PLASTICS: Since early studies highlighted how fish exposed to sewage effluents were changing sex, attention has been focused on the effects of these chemicals on human fertility, which has shown a marked decline over recent years. Though water companies operate under specific codes of practice to prevent plastic resins, cements and linings from leaching foreign substances into the supply, there have been several incidents where they have failed to prevent contamination. Also under scrutiny are pesticides, which work their way into the ground and river systems from industry, agriculture and even households. These can mimic the action of hormones in the body, and are increasingly suspected as one factor lying behind the rising rates of hormone-related cancers in industrially developed nations. Carbon filters, similar to activated carbon, can remove pesticides and chemicals from plastics, but only where the carbon is in solid form. Many plumbed-in, ceramic or reverse osmosis systems can have this feature incorporated within them.

FLUORIDE: Fluoride, which can occur naturally in water, helps strengthen children's teeth as they develop. But too much can cause fluorosis - an unsightly permanent brown mottling of the teeth. Because many toothpastes and mouthwashes already contain fluoride - and as children often swallow toothpaste - some experts argue that fluoridation of water supplies could increase the number of people potentially at risk of fluorosis.

HEAVY METALS: While trace elements of many metals (such as magnesium and selenium) are necessary for good health, some, like lead and aluminium, are not. Aluminium can occur naturally, but many water companies still treat water using aluminium sulphate. Both lead and aluminium poison the internal organs before settling in the brain and bones. Excess aluminium is widely believed to trigger Alzheimer's disease, which causes dementia as the brain is rapidly destroyed. These and other metals with similar effects like silver, cadmium and mercury can be effectively removed by several methods including distillation.

HARD & SOFT WATER: Calcium and magnesium make water hard. Levels of hardness vary naturally throughout the country. But there is an increasing body of evidence suggesting that the higher levels of these minerals in hard water may protect arteries from heart disease.