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Expert Speak

Potability of Ground water

He is the ground water guru in this part of the world. Dr Felix Ryan holds a doctorate in Environmental Science from the university of Arizona. He was an advisor to the United Nations, and has worked in many countries on groundwater projects. Has served the Government of India in various capacities. In 1989 UN declared him a Global Environmentalist.

“The quality of groundwater, as a source of potable water, throughout the world is substandard. There may be a spring in some areas that may give truly fresh and potable water. But these are rare,” says Dr Ryan. “In India the groundwater table is receding faster than it is in the rest of the world. The result is that we can get a cola or whisky easily but not a bottle of pure water!”

More ironies emerge as we talk to him about a simple basic human need and right – Fresh water. He feels that centralised storage and distribution of water may not be the best solution to meet the needs of an expanding population. He believes that we must be looking at using sea water for a range of uses from the domestic to agricultural. While he advises governments and planners, he has solutions for the individuals and small communities, because he believes firmly, ”The poor will remain poor if they depend on the technology of the rich.” He proves his point with, “Do you realise that a litre of water we pick up in a supermarket is as expensive or more than a litre of milk?”

Some insights into ground water and management from Dr Ryan

Common ground water pollutants. Causes

  • Fluorides

  • Arsenic

  • Lead

  • Mercury

  • Cadmium

  • Chromium

  • Selenium

  • DDT and other Pesticides

  • Can ground water be made safe to drink? How?

  • Distillation

  • Filtration

  • Duckweed

  • Improving Water Quality

  • Testing Ground water quality

  • What are the common ground water pollutants in urban areas in India? What is the cause of such pollution?

    We have two types of pollutants: pathogens like disease causing bacteria that may enter the water system when contaminated with sewerage. The other type of pollutants are inorganic salts and heavy metals. This happens because many of our landfills do not have a protective bottom paving. So when it rains all the hazardous wastes dumped in the landfills percolates into the soil as do industrial effluents.(Hence landfills are prohibited in the UK.)

    Tamil Nadu has a high content of Fluorides and West Bengal has Arsenic content in water. Some of the other common solvents are:

  • Lead

  • Mercury

  • Cadmium

  • Chromium

  • Selenium

  • DDT

  • Fluorides

    Occurrence:

    The majority of fluorine/Fluorides found in nature are present in various rocks, soils, waters, plants and other living organisms, slag and fluxes. The atmosphere contains very small amounts of fluorine.

    However the content of fluoride is high in industrial areas, especially near aluminum plants and near factories manufacturing super phosphate fertilizers.

    Permissible Limit: 1.5 mg/L ( WHO standards)

    Effects of Fluoride:

    Fluoride is essential in small quantities for the prevention of dental caries, especially in children.

    Excessive consumption leads to:

    • Skeletal Fluorosis: Deposits of Fluoride on the bones, making them stiff and rigid with a crippling effect.

    • Dental Fluorosis: Discolours teeth, makes teeth brittle and eventually makes them fall out.

    • Blood Disorders

    Arsenic

    Occurrence:

    In the natural environment, arsenic occurs in soils at an average concentration of about 5 to 6 mg/KG.

    Geological processes release Arsenic into ground water. As also human activity like overuse of groundwater, use of chemical fertilizers, manufacturing, mining, smelting etc. Living next to hazardous waste dumps and consuming polluted ground water is a health hazard. Inorganic Arsenic is more harmful than organic arsenic compounds.

    Permissible Limit:

    As per WHO standards, permissible limit of arsenic in drinking water is 0.01 mg/litre and as per BIS, permissible limit is 0.05 mg/litre.

    Effects of Arsenic:

    • Consuming high levels of inorganic arsenic can result in death.

    • Small levels of arsenic can cause nausea and vomiting.

    • Arsenic ingestion can cause blood disorders.

    • Ingesting or breathing low levels of inorganic arsenic for a long time can cause skin problems.

    Lead

    Occurrence:

    A naturally occurring metal. A very useful element, used in batteries, ammunition, soldering etc.

    Lead compounds are found in fossil fuels and paints. How much lead leaches into the soil depends on the soil quality.

    Permissible Limit:

    As per WHO standards, permissible limit of lead in drinking water is 0.01 mg/litre

    Effects of Lead:

    Lead can affect almost every organ and system in your body. The most sensitive is the central nervous system, particularly in children. Lead also damages kidneys and the reproductive system.

    Mercury

    Occurrence

    Metallic mercury is used to produce chlorine gas and caustic soda, and is also used in thermometers, dental fillings, and batteries. Industrial effluents seep into the ground water and water resources leading to pollution.

    Permissible Limits

    As per WHO standards, permissible limit of Mercury in drinking water is 0.001 mg/litre

    Effects of Mercury

    Exposure to high levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing foetus. Effects on brain functioning may result in irritability, tremors, changes in vision or hearing, and memory problems

    Cadmium

    Occurrence

    Cadmium of various valences and their compounds occur naturally. Cadmium has many uses including batteries, pigments, metal coatings, and plastics. Ground water is polluted with Cadmium by runoffs from factory wastes and landfills.

    Permissible Limits

    As per WHO standards, permissible limit of Cadmium in drinking water is 0.003 mg/litre

    Effects of Cadmium

    Long-term exposure to cadmium in water is associated with kidney disease. Other long-term effects are lung damage and fragile bones. May have carcinogenic properties.

    Chromium

    Occurrence

    Chromium occurs in different forms naturally. It is used for making steel, chrome plating, dyes and pigments, leather tanning, and wood preserving.

    Permissible Limits

    As per WHO standards, permissible limit of Chromium in drinking water is 0.05 mg/litre

    Effects of Chromium:

    Ingesting large amounts of chromium can cause stomach upsets and ulcers, convulsions, kidney and liver damage, and even death.

    Selenium

    Occurrence

    Selenium levels in drinking-water vary greatly in different geographical areas but are usually much less than 0.01 mg/litre. Foodstuffs such as cereals, meat, and fish are the principal source of selenium in the general population. Levels in food vary greatly according to geographical area of production.

    Permissible Limits

    As per WHO standards, permissible limit of Selenium in drinking water is 0.01 mg/litre

    Effects of Selenium:

    Some selenium is essential for humans and forms an integral part of the enzyme glutathione peroxidase and probably other proteins as well.

    In humans, the toxic effects of long-term selenium exposure are manifested in nails, hair and liver.

    DDT and other pesticides

    DDT (dichlorodiphenyltrichloroethane) is a pesticide once widely used to control insects in agriculture and insects that carry diseases such as malaria. DDT is a white, crystalline solid with no odour or taste. Though it has been banned in many countries including India, wells in agricultural areas may have accumulated DDT and other pesticides through seepage and run off during monsoons.

    Permissible Limit:

    As per Bureau of Indian Standards, permissible limit of a pesticide in drinking water is 0.01 mg/litre

    Effects of DDT on Health:

    • Affects the nervous system

    • In women it affects lactation and gestation.

    Organochlorines and organophosphorus:

    Limits 0.0001mg/l;for one and 0.0005mg/l for all together

    Effects of pesticides on health:

    Organochlorines bioaccumulate in body fat. Lindane affects Central Nervous system, is a carcinogen.

    Malathion interferes with the chromosomal set up.

    Chloropyrifos affects the neural system of the foetus.

    Can ground water be made safe to drink? How?

    The question cannot be answered with a simple yes or no. Theoretically it can be done. At a laboratory level it is possible. But on a commercial scale it is very expensive.

    For example, we can get rid of the pathogens by filtering, boiling and filtering again. Some of the dissolved salts can be separated by Reverse Osmosis (RO). (The membrane used for RO is, however, expensive and has to be changed frequently). We have a problem with dissolved heavy metals and compounds.

    Distillation

    Distillation is a possibility. In distillation, water is boiled to produce steam. As the steam separates from the water it leaves behind solids and dissolved gasses are driven off. This steam is then condensed into purified water and collected in a tank and stored for use as needed.

    This can be done at home also. Fill a metal pot with boiling water. In the middle of the pot have an empty container. Cap the pot with a cone shaped lid. Keep cold water in the cone. The steam from the water rises up hits the conical surface and drips from the tip of the cone into the empty container in the pot. This is pure water. The only problem is to keep the water inside the cone cold so that the steam rising from the pot condenses on hitting the cooler surface. In fact, the Ryan foundation is developing a pressure cooker type gadget that can do this with tap water effectively.

    Filtration

    The three pot filtration system is an effective one. Three pots are placed one over the other. The first two pots have a small hole at the bottom. The hole is covered by a mesh. The first pot has a layer of clean river sand and over it a layer of small pebbles.

    The second pot has charcoal and the third has a piece of Alum. This method filters out some suspended particles, sediments out some chemicals.

    Duckweed

    Duckweed is a small aquatic plant that grows and floats on water. Research has shown that duckweeds are especially adept at removal of phosphates and nitrogen, particularly ammonia dissolved in water. You can write to FAO in Delhi for more information on duckweed. You can grow duckweed in your well or tank as a purifying agent.

    What are the methods by which ground water quality can be improved in urban areas?

    There are some issues to be noted regarding water supply in Indian metros:

    • Most cities have areas where the municipal supply runs through pipes laid in the British times with “ Birmingham pipes”. They have rusted and have perforations and holes.

    • Three or four lakes/catchment areas feed large populations. Such centralisation is difficult to monitor, with water losses inevitable along the way. The water stored may not be adequate, especially if monsoons fail and wells do not supplement municipal supply.

    • The water table is receding at a grater pace that it is in many other parts of the world. So we find borewells that gave water last year may not give water this year.

    All this leads to indiscriminate use of groundwater.

    As remedial measures we have the following;

    1. Reverse Osmosis of sea water: This has been tried near the Chennai coast. Though reasonably good water was obtained from the process, bottling and transportation cost make the water as expensive as Rs 20/ a litre.

    This solution is viable only for big organisations like Five star hotels, schools, hospitals and other big institutions.

    2. Rainwater harvesting is being advocated vigorously. We do not know how effective this will be in the short term. Rainwater put back into the well or ground near your house may enter a basin far away and may not reach the spring that is feeding your well or bore. Or it may just dissipate in the dry soil or be absorbed by plants in the area. This is especially so because of the receding water table.

    I am experimenting with the storage of rainwater in hollow pillars in an apartment block for usage in the dry months.

    Rainwater harvesting is a remote and long term solution.

    To me it seems that saline water has to be used for some of our needs to reduce the demand on freshwater. In Hong Kong sea water is used to flush toilets.

    In Sharjah, UAE, sea water is used in a swimming pool.

    There are several low investment low technology methods of desalinating sea water that I have discussed in my books Water managements in Homes and Villages and How to convert Sea water into Drinking water.

    Are there places where we can get the ground water tested for solvents? How should we prepare the sample for this?

    The Indian Bureau of Standards has set limits for solvents in Water. Potable water is tested for 25-30 parameters that include organic and inorganic solvents. Most Cities and towns have testing facilities as part of the Metrowater/Municipal Supply departments.

    There are kits that are commercially available for testing water. There is one kit that has been developed by Defence Food Research Laboratory, Mysore and one has been developed by E Merck of Germany.

    A sample of five litres has to be taken for testing. It must be taken in a clean and dried (not wiped) bottle. If it is well water, it should not be immediately after a rainy spell.

    In Chennai water can be tested at:

    1. C P R Environmental Education Centre,
    1 A, Eldams Road,Teynampet,Chennai-600018
    Ph: 24346526

    2. King Institute, Guindy Ind Estate,
    Chennai-600032
    Ph: 22341026

    3. Chief Water Analyst.
    TWAD Board,
    31,Kamaraj Salai,
    Triplicane, Chennai-600005
    Ph: 28412098



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