ROTARY CLUB OF MARUTERU

DISTRICT SEMINAR ON NEW GENERATIONS

AT

RC PENUGONDA (Dt.24-09-2006)

SPEECH

OF

DTS REDDY

ON

 POTABLE WATER

Definition: The water which Safe to Drink is called potable water, The water required for domestic consumption should possess a higher degree of purity and it should be free from suspended impurities, chemical impurities & Bacteriological impurities etc.

Following are the requirements of potable water.

1)                 It should be clear, odourless, colourless

2)                  It should be free from harmful and disease producing bacteria.

3)                 It should be free from objectionable substances.

4)                 It should be fresh.

5)                 It should be palatable, i.e., aesthetically attractive,

6)                 It should be tasty.

7)                 It should not cause corrosion to pipes and other fittings.

Impurities in water: It is not possible to find pure water in Nature. The rain water as it drops down to the surface of earth, absorbs dust and gases from the atmosphere. It is further exposed to organic matter on the surface of the earth and by the time, it reaches the source of water supply, it is found to contain various other impurities also. For the purpose of classification the impurities present in water may be divided into the following three categories.

1)                 Physical impurities

2)                 Chemical impurities

3)                 Bacteriological impurities.

Under above categories tests are carried out to examine water :

1.1)Colour: The measurement of colour in water is carried out by means of TINTOMEATER  i.e., cobalt scale  numbers. The number on cobalt scale should not exceed 20 and should be preferable less than 10. Excess colour spoils the cloths.

1.2)Taste and Odour :  The water possesses taste and odour due to various causes and they make the water unpleasant for drinking. The taste and odour, tested by  threshold number method, for public water supply the threshold number should not be more than 3.

 1.3)  Temperature : The desirable temperature of potable water water is 10degrees

 centigrade

1.4) Turbidity : the colloidal matter and clay and silt  present in water imparts turbidity.  by means of turbidity meter we will measure turbidly the permissible limit is 5 to 10 PPM

2) Chemical impurities :-

2.1) Chlorides : The excess presence of  sodium chloride indicates pollution of water due to sewage and minerals. The highest desirable level of chlorides content is 200 mg/Lit and maximum permissible level is 600mg/lit

2.2) Dissolved gasses: The water contains various gases from its contact with the atmosphere and ground surfaces. The usual gasses are nitrogen, methane, hydrogen sulphaide, carbon dioxide, oxygen. 5 to 10 p.p.m. dissolved oxygen is required for potable water.

2.3)           Hardness : soap destroying power of a water is two types

i) Temporary hardness: due to bicarbonates of calcium and magnesium, it can be removed by boiling or by adding lime.

ii) Non carbonate hardness: is due to presence of sulphates, chlorides and nitrates of calcium and magnesium. It can not removed by simple methods . It requires special methods. The excess hardness of water is undesirable. It causes more soap, provides scales in boilers. Causes corrosion and incrustation of pipes, make food taste less. By means of soap solution method the degree of hardness may be measured. The water having the hardness of about 5 degrees is reasonable soft water and a vary soft water is tasteless. Hence potable water, the hardness should preferable 5 degrees but less than 8 degrees.

2.4)     Hydrogen ion concentration: ph value, It should be 7 to 8.5

2.5)          Nitrogen and its compounds: Free ammonia should not exceed 0.15ppm,  albuminoidal ammonia (used to represent the quantity of nitrogen present in water before decomposition of organic matter) should not exceed 0.3ppm .  The presence of nitrites indicates organic matter present in water is not fully oxidized. it should be nil. The presence of Nitrates indicate s that the organic matter in water is fully oxidized and the water no longer harmful The highest desirable level is 45mg/lit

2.6)           Total solids: Total amount of dissolved and suspended mater present in the water. The highest desirable level is 500mg/lit and the maximum permissible level is 1500mg/lit

3) Bacteriological impurities: The many of the bacteria found in water are derived from the air, soil, vegetation. Some of these are able to multiply and continue their existence while the remaining die out in the due course time. The potable water should free from pathogenic bacteria.

Water Born diseases: The water is considered to be an important agent for carrying and spreading some of the dangerous diseases like , cholera, dysentery, typhoid and partly responsible for other diseases  such as hepatitis , tuberculosis, gastro-enteritis and poliomycities. The patients suffering from such diseases give out the organisms responsible for such diseases from the intestinal discharges, such organisms then some how obtain entrance to the sources of drinking water and the diseases is thus further carried forward.

            It is significant to note that water-borne diseases are predominant in developing countries.  It is estimated that about five million babies die annually from water-borne diseases, one in six of the world population suffer every year from water-born diseases. The survey conducted by World Health Organization indicates that about 86% of the population in rural areas is with out reasonable access of safe water. It is therefore very clear that the battle with water-borne diseases will be finally won by continued attention to pollution prevention and maintaining quality of water up to required standard…………….