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 Frequently asked questions

 Why water is saltish ?

     Chlorides give water a salty taste, but the intensity of the taste depends upon the ionic composition. Thus in some waters the salty taste is detected at about 200 mg/lit but if the water contains high concentrations of calcium magnesium, the salty taste is not noticed even at 1000 mg/lit.

 Why water on standing becomes turbid and brownish yellow?

     Normally some ground water may contain ferrous iron in the form of its bicarbonate, which is in dissolved condition. On exposure to air, ferrous iron is oxidised to insoluble ferric iron hydroxide and is seen in the form of brownish yellow precipitate.

 Why soap is not lathering ?

    This is due to the property of excessive hardness in water. Hardness is mainly contributed by calcium and magnesium.

 Why boiled rice is hard and yellow in colour?

     This is due to the property of high alkalinity in water. Alkalinity is mainly contributed by bicarbonate.

 Why dhal becomes hard on cooking ?

    This is due to high alkalinity of water.

 Why boiled meat/ food becomes poor in quality ?

    This may be due to the high hardness of water.

 What is the reason for algae growth ?

     Trace level of phosphorous and nitrogen aid for algae growth. Sunlight or stray light can help this process.

 How white deposits in vessels (when water is stored/boiled) ?

     The scales are due to precipitation of calcium carbonate from water. Scale formation is notable when the water is temporary hardness. The water after filtration can be used without any harm.

 What is the reason for oily suspensions noted on the surface of water in wells ?

     This is also due to precipitation of calcium carbonate in water.

 How white deposits blocking the PVC pipes ?

     This is due to deposition of calcium carbonate scales. This is found particularly when compressor pumps are used.

 How horizontal brownish or brownish-black streaks found in teeth ?

     This is caused in children due to excess fluoride in water. The horizontal streaks formed are permanent and cannot be treated or removed.

 Why rotten egg smell occurs in water ?

     In the absence of sufficient air and under anaerobic conditions, hydrogen sulfide is formed due to putrefaction of organic matter in water. This causes rotton egg smell in water.

 Why brownish or brownish-black slimes formed in water conveying pipes ?

     May be due to growth of iron bacteria in water.

 Explain the death of infants due to blue baby disease ?

     High nitrate in water causes blue baby disease. The blood of the children affected by the disease turns blue and the children die of asphyxiation. The disease affects only infants below six month age. Adults are not affected. Breast fed children are not affected by this disease.

 How clothes loose their shining and become dirty after some washings ?

     This is due to presence of high hardness and iron in water used for washing. Good lathering can occur with detergents but the cleaning action in hard water will not be always satisfactory.

 Explain reason for formation of slime in closet in toilets and in the floors of bathroom ?

     This happens due to microbial causing micro-organisms (called pathogens) in water.

 Can we use alum or permanganate for water purification ?

    Except bleaching powder, no other chemical is recommended for use by the public at household level.

 Can we ues ?nellikattai (emblica species), for reduction of salt and improvement of taste of water ?

     'Nellikattai' may improve the taste but cannot reduce the salt content or other harmful effects of water.

 Can we use?thethankottai (strychnous potatorum )' for water purification ?

     Thethankottai' is a natural coagulant and removes only turbidity and can be used for removal of turbidity

 Whether the presence of septic tank may affect the quality of water in nearby wells?

     If the seepage from septic tank mixes with well water, it can definitely affect the quality of water and can cause water borne disease. Mixing of septic tank waste or sewage in drinking water can be easily identified by test in for ammonia, phosphate and fecal coliform. There should be sufficient distance (at least ?20-50?) between the septic tank and a well

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