Global Distribution of Fresh Water

Sr. No.	Fresh water	Expressed in Cubic Kms.
1.	Water in ice sheets, snow cope and glaciers etc.	24,000,000
2.	Ponds, lakes and reservoirs	280,000
3.	Streams and rivers	1,200
4.	Soil moisture	85,000
5.	Ground water and well water	60,000,000
	Total amount of fresh water	84,366,200

The use of water can be considered under two categories namely.

(i) Consumptive and partially consumptive

(ii) Non consumptive.

The first category comprises such uses as domestic water supply irrigation and requirement of industries and power generation with fossil and nuclear fuels.

The second category encompasses hydropower, generation, navigation, pisciculture, recreation wild life preservation and river conservancy. Almost 76% of total used by man has to utilized to grow food following agriculture. Power generation (6.2%) and industries (5.5%) domestic requirement and stock management taken together (4.67%) of total drawn. A large fraction is returned to the surface deposits or stream flows often in a polluted stated which can be reused as such or after treatment to remove impurities out of the total quantity of water drawn the amount of water irrecoverable consumed was estimated to be about 2,200 cubic kms. (L’ vovich 1989) the approximate requirement of fresh water in India as estimated for the year 1974 A.D., 2000 A.D. and 2025 A.D.

Water herd	1974	2000	2025
Irrigation	350.0	630.0	770.0
Thermal power generation	11.0	60.0	160.0
Industries	5.5	30.0	120.0
Domestic requirement	8.8	26.6	39.0
Lince stock management	4.7	7.4	11.0
Total	38.0	754.0	1,1000

Potable Water

The water which is safe to drink is potable water. However does mean distilled or pure water. Potable water fit for human consumption, should satisfy the following essential requirement.

(1) It should be sparking clear and orderless.

(2) Pleasant in taste.

(3) Perfectly cool

(4) Turbidity should not exceed 10ppm.

(5) It should free from objectionable dissolved gases like H₂S.

Technique employed the analyses of water

Polythene bottles of 2.5 litre capacity are used as sample container.

Sampling Techniques

For the analysis of ground water, two principal types of sapling procedures^13/14 are employed.

1. Spot or Grab samples sport samples are discrete portions of water samples taken at a given time. A series of grab samples, collected from different depths at a given site, reflect variations in constituents are period of time.

2. composite samples when the grab samples of a particular water is collected at a regular interval for a specific period such as 12 hours or 24 hours and mixed, then the integrated sample is called composite sample.

When liquid is homogeneous, it is sufficient take the grab sample only. The sample bottle should first be rinsed with the liquid being sampled and then filled.

When liquid to be sampled is heterogeneous such as sewage a composite sample is necessary of any constituent to be determined is affected by air contact take the sample out of contact with air and completely fill the container when hot sample are taken they must be cooled using cooling coils. The tap should be cleaned inside and outside then collect the sample the water being sample should then be allowed to waste for sometime so that the sample will be representatives of the whole supply.

Then water from well is collected then well has to be pumped for a sufficient time such that the sample represent the ground water that feeds the well. Samples are taken at the mid point of livers and scheme. Collect samples at least 0.6 to 1 km. below dams or water sample keep out of light and low temperature (4°C) white. Determination like Ph, dissolved gases as O₂, CO₂ and H₂S were made immediately while other constituents analyzed after sometime.

Chemical Substance Affecting Portability Colour

This test is usually applicable to drinking water and potable water. It was carried out by comparison with known colour standard⁵. Colour in water may be due to presence of fine particles in suspension or due to certain mineral matter in solution. Even pure water is not colourless and it has been found to have a pale green tint in large quantities. The three colour of a water sample is due to the substances present as fine collides, colour is measured with an instrument known as tinto meter. The unit of colour is measured on the platinum cobalt scale and expressed in Hazen units. The standard colour can be produced by dissolving 1 mg. of platinum Cobalt in one litre of double distilled water.

Turbidity

Turbidity in water is due to colloidal and extremely fine dispersions. Suspended matter such as clay, silt, finely divided organic and inorganic matter, plankton and other macro-organisms also contribute turbidity. Turbidity can be measured by visual method and instrumental methods such as absorptiometrically or nephelometically. The standard unit of turbidity is considered as that produced by one ppm of silica in the form of diatomaceous earth. Turbidity removed by setting or by centrifuging.

Odour

Odours in water are due to presence of microscopic organisms or delaying vegetation including algi, fungi, bacteria, actinomycetescets and weeds¹⁶. Sewage and industrials effluents cause offensive odours to receiving waters. The extent of odour depends upon the pH of water-lower the pH higher will be the amount of hydrogen sulphide produced.

For example, the protozoa, dinobryon imparts a fishy odour in water. The algae oscilltory and rivularia produce mouldly odour and algae anabaena a strong grassy odour. Mineral matters such as sand and clay when present in finely divided state produce a faint earthy taste and odour in water.

To determine the hot odour quality take 250ml sample in a 500ml stoppered conical flask and heat to 58-60°C. Sniff the odour which may be:

(i) Aromatic (ii) Chlorinous

(iii) Chemical (iv) Medicinal

(v) Sulphuretted (vi) Septic

(vii) Earthy (viii) Peaty

(xi) Grassy (x) Moldy

(xi) Fishy (xii) Disagreeable

(xiii) Vegetable (xiv) Putrid

(xv) Wormy

The intensity of odour is expressed in terms of Threshold Odour Number. For drinking water TON should not exceed three.

Taste

Taste is always accompanied by odour. However, dissolved mineral matters produce tastes but not odour. A faint bitter taste may be due to the presence of sulphate while soapy or inky taste may be due to excess of sodium carbonate. Water containing unusual salt content have a brackish taste. Dissolved gases, minerals, nitrates and carbonic acid make water palatable.

Temperature

Surface waters differ considerably in temperature between winter and summer. Temperature measurements are useful in detecting an unsuspected source of pollution, in calculating alkalinity and in industrial water supplies for heat transmission calculations Hydrogen Ion concentration (pH).

pH, a measure of hydrogen ion activity, is used to express the intensity of acidic or alkaline condition of a solution. it is also an important factor water to 100ml in volumetric flask at 25°C.

pH 7 Buffer Solution

dissolve 1.361g anhydrous potassium dihydrogen phosphate (KH₂PO₄) and 1.420g sodium dihydrogen phosphate (NaH₂PO₄) in distilled water and make up to 1000ml in a volumetric flask.

pH 9 buffer solution

dissolve 3.81 borax (Na₂B₄O₇.10H₂O) in distilled water to 1000ml.

(i) The desirable pH range for drinking waters is 7.0 to 8.5.

(ii) pH in conjunction with total salinity and temperature is used to determine whether a water is corrosive in nature or having scale forming tendencies.

Electrometric Method for the Determination of pH

Electrometric determination of pH involves the measurement of (EME) of a cell comprising an indicator electrode (glass electrode) responsive to hydrogen ions and a reference electrode (calomel electrode)

pH 4 Buffer Solution

dissolve 1.012 anhydrous potassium hydrogen phthalate in distilled. Its unit is micromhos/cm or micro siemns/cm³. Conductity of water varies directly with the temperature and is proportional to its dissolved mineral matter content.

Specific Conductance

specific conductance is the conductance of one centimeter cube of a solution of an electrolyte. It is generally denoted by k (Kappa) thus

k = 1/P

A simple conductivity meter with dip-type cell was used for the analysis of water samples. The instrument and the cell was calibrated by using 0.005M KCI solution (Conductivity = 654 mho cm^-1).

Acidity

Mineral Acidity

Took 50ml or suitable dechlorinated aliquot of the sample in a 250ml conical flask. Added 2 drops of methyl orange indicator and titrated with 0.02N-NaOH solution till faint orange colour.

Calculation

Acidity as CaCO₃ mg/L =

Results

Methyl orange acidity value shows mineral acidity. In absence of mineral acidity, total acidity is only the CO₂ acidity of the water sample.

Alkalinity

Alkalinity of water is due to the presence of carbonate and hydroxide ions. Determination of alkalinity by Titrimetric method principle alkalinity was determined by titration with 0.02 NH₂SO₄ using methyl orange and phenolphthalein as indicators.²⁰

Reactions

2CaCO₃ + H₂SO₄ CaSO₄ + Ca(HCO₃)₂

Ca(HCO₃) + H₂SO₄ CaSO₄ + 2CO₂ + 2H₂O

Ca(OH)₂ + H₂SO₄CaSO₄ + 2H₂O

Total hardness (Ca and Mg)

The hardness of water is not a pollution parameter but indicates water quality, mainly in terms of Ca²⁺ and Mg²⁺, expressed as CaCO₃. The analysis is done by complexometric titration.^21,22

Classification of Hardness

Hardness has traditionally been divided into temporary and permanent hardness.

Temporary Hardness

The portion of hardness which disappears on prolonged boiling is called temporary, hardness. It is caused by bicarbonates of Ca²⁺ and Mg²⁺.

Permanent Hardness

The hardness that remains after boiling is called permanent hardness. It is caused by the presence of sulphate, chlorides, nitrates of Ca²⁺ and Mg²⁺.

Determination of total hardness

Principle

During titration with EDTA (Na₂H₂Y), Ca²⁺ first reacts to form relatively stable CaY^2-, followed by Mg²⁺ to give MgY^2- complex (indicator/wine red) releasing the free indicator (blue). The colour changes from wine-red to blue at the end point.

Reaction

Eriochrome Black T

{1-(1-Hydroxy-2-naphthylzao-6-nitro-2-naphthol-4-sulphonate)}

This gives total Ca²⁺ and Mg²⁺ Next from a aliquot of the sample, Ca²⁺ is estimated selectivity at pH 12.3 (Mg²⁺ gets precipitated as Mg(OH)₂ in presence of cation indicator. The colour change is from pink to blue.

Calcon

[1-2 (Hydroxy-1-naphthylzao)-2-naphthol-4-sulphonate]

Total hardness (Ca and Mg)

Total hardness of water is not pollution parameter but indicates water quality in term of Ca²⁺ and Mg²⁺ expressed as CaCO₃. The total hardness is also expressed in ppm. The analyses is done by complexometric titration using EDTA. The hardness of water reflects the nature of geological formation with which the water is in contract. Ground water³⁰ may be hard due to the natural accumulation of salts from contract with the soil. Generally surface water are softer than ground well waters. Total hardness is calculated by adding the multi equivalents of Ca and Mg per litre and multiplying the sum by 50.

According to the degree of hardness the waters are commonly classfied³¹ as per U.S. Geological survey as illustrated in table.

Table : Classification of Hardness

Total hardness as CaCO₃ in mgk	Classification
0-55	Soft
50-100	Slightly hard
101-200	Moderately hard
201-500	Very hard

On examining the table total hardness value ranges in between 100 to 4300ppm. These results indicate that the ground water of this region in very hard in nature. Hard water of these wells are reported to cause no harmful effect upon the health of consumers. The use of hard waters however is limited because of excessive soap consumption in homes. Hard water form incrustation untensils and the vegetables cooked in it get toughened.

Total dissolved solids

In natural waters, the dissolved Solids consist mainly of bicarbonates, carbonates, chlorides, sulphate, nitrate and possibly phosphates of calcium, magnesium, sodium and potassium with traces of iron and other substances. In the percent study the total dissolved solids range between 120 to 40,700 ppm in the water samples. The WHO International³² standards set the permissible³³ limit for total dissolved solids as 1000 ppm and excessive limit as 3000ppm. Thus water for domestic and industrial uses should have TDS value of less than 1000ppm. And for agriculture utility the optimum range should be below 3000ppm. In the percent investigation the TDS value lies between 175 to 4300 ppm.

Sodium

Sodium is a major component of potable waters. Most of the sodium compounds are water soluble and do not play any role in the incrustation of wells. The primary sauce of sodium in natural water is from the release of soluble products – All natural waters contain meouble³⁴ amount of sodium.

Calcium

Calcium is an essential element and human body requires approximately 0.7 to 2.0g of calcium per day as a food element. However waters with high calcium content are undesirable for washing, bathing and laundering because of the consumption of more soap and other clearing gents sub surface waters in contact with sedimentary³⁵ rocks of marine origin drive most of their calcium for the solution of dolomite, anhydrite and gypsum.

Surface water in equilibrium with atmospheric carbon dioxide can contain as much as 20ppm to 30ppm of calcium at saturation. In the present in investigation the calcium concentration lies between 24 to 1544 ppm.

Magnesium

Magnesium is an essential element for human beings. Magnesium is relatively non-toxic to man. However, a higher concentration causes unpleasant taste to water. At high concentrations, magnesium salts have a laxative effect particularly when present as magnesium sulphate.

Despite higher solublities of most of the magnesium compounds, magnesium is generally found in lesser amount in natural than is calcium. In contrast with most natural water, sea water contains above five times as much magnesium as calcium. The deficiency of calcium in sea water is undoubtedly due to the preferential abstraction of calcium by plants and animals.

Common concentration of magnesium range from about 1 to 40 ppm, water from rocks rich in magnesium may have as much as 100ppm, but concentrations more than 100 ppm rarely encountered except in sea water and brines. Exceptionally low values of calcium and magnesium are found in some waters which have undergone natural softening by cation exchange.

Fluoride

Source of fluoride in ground water are minerals like calcium fluoride, apatite cryohite and fluorspar in sedentary rocks. Presence of fluoride in drinking water in beneficial³⁶ because it reduces tooth decay. At higher levels, however mettling of the teeth occurs. For this reason maximum fluoride concentrations recommended for drinking water as per WHO or ICMR standards range from 1.4 to 2.4ppm depending on how much water is ingested. In the present investigation the fluoride concentration ranges in between 0.1 to 1.85 ppm.

Chloride

Chloride is a major dissolved constituents of most natural water. The concentration of C1 ions varies team sample to sample under investigation. Chloride produces a salty taste to all well waters, but the salty taste is variable. Reasonable amounts of chloride are tolerable in many water supplies. Chloride salts are highly soluble in water so they can not be removed simply by precipitation.

Chloride is also free from the effects of exchange, adsorption and biological activity. Chloride concentration found in natural water vary between 0.1 ppm in arctic snow to 150,000 ppm in brines. Continental³⁷ rain and snow may contain from 1.0 to 3.0 ppm of chloride.

1.village – dighal

pH 7.9

E.C(µmhos/cm) 1500

TDS 380ppm

Hardness 280ppm

Ca²⁺ 52.0ppm

Mg²⁺ 36.0ppm

Cl^- 90ppm

Na⁺ 6.8ppm

Result – water is potable here. All constituents present within the limit.

2. VILLAGE – GUDDA
pH	8.4
E.C	3700
TDS	90
Total Hardness	460
Ca²⁺	96.0
Mg²⁺	50.8
Cl^-	150
Na⁺	17.8

Result: water is potable here.

3. VILLAGE - SHERIA
pH	8.0
E.C	1000
TDS	640
Total Hardness	400
Ca²⁺	76.0
Mg²⁺	38.0
Cl^-	240
Na⁺	4.4

Result: As all the value lies within the limit. Thus sample is potable.

Suggestions and Conclusions:

Water is an indispensable need^39-41 of life. We are now near the stage when surface and ground water has become a global problem partly because of the population explosion and partly due to phenomenal advances in industrialization. Now there is the need to prevent water borne diseases such as typhoid, chlorea, diarrhea and dysentery etc. The water quality of wells needs a betterment in which can be achieved by considering the following suggestions :-

1. The contaminant sources near the wells should be carefully surveyed so that there is no seepage of toxic constituents.

2. Location of wells for drinking water supplies should be decided with utmost caution.

3. Surrounding contaminant’s sources and flow direction of effluents should be considered.

4. It is not advisable to tap the uppermost acquifer in case of drinking wells.

5. Location of industrial and municipal disposal sites should be decided keeping in view the ground (well) water levels and flow patter in the area.

6. In case of toxic industrial effluents, steps should be taken for predisposal treatment by the industry itself.

7. Industries must also learn to do a better job of controlling the release of its pollutants or thermal discharges.

8. The 4R concept i.e., recycling, renovation, recharge and reuse should be employed in the modern technology of waste water treatment.

9. All disposal of solid wastes near the well waters or the various channels need to be curtailed.

10. Most of the municipalities still use the inadequate primary treatment. So there is an urgent need to design sewage treatment facilities so that BOD load on receiving water is reduced.

11. Water quality of the wells rivers need to be monitored and controlled in a sustained manner for human use and sustenance of the ecosystem.

12. More treatment plants should be created for treatment of effluents. Discharge of raw sewage, sullage and sludge should not be allowed in the water bodies.

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Received on 04.12.2012

Modified on 12.12.2012

Accepted on 18.12.2012

Research J. Science and Tech. 4(6): November –December, 2012: 267-273