Impurities of water known by following parameters :

Physical parameters

Chemical parameters

Biological Parameters

1. Physical Parameter :

The parameter which can be felt or sensed by any of our senses are referred as physical water quality parameter. The following parameter define physical water quality

I. Temperature

II. Turbidity

III. Taste and Odor

I. Temperature :

• Temperature affects the chemical and biological reactions

• An increase 10° C almost doubles biological reactivity

• For water supply temperature between 10 and 20

II. Colour:

• Neutral water does not have any color . The presence of organic and inorganic matter in water gives the colour blue black red etc

• Colour in water measured by a device known as tintometer

• Unit of measurement of intensity of color in water is TCU(True color unit)

III. Turbidity :

• Suspended particles like clay, silt, plant fiber etc makes water turbid

• Turbidity can be measured by using turbidity meter, turbidity rod

• The unit of measurement is NTUC (Nephelometric turbidity unit)

IV. Taste and Odour:

• Taste and Odour are caused by dissolve gasses like hydrogen sulfide,methane,organic matter or form inorganic matter

• Pure water is tasteless and odourless

• Intensity of taste and odour is expressed by TON

2. Chemical Parameter:

I. Total Dissolve Solids (TDS)

II. PH

III. Hardness

IV. Chloride content

V. Nitrogen content

VI. Metal

TDS:

• They composed of inorganic salts, mainly the chlorides, sulphate and bicarbonates, magnesium, potassium and sodium.

• TDS in water is estimated by simple evaporation method and by measuring electrical conductivity of water.

• Unit of measurement of TDS is mg/l

pH

• It is a scale which is used to indicate the acidity or basicity of water in the range of 0-14

• pH value is measured by pH meter or by using pH paper

Hardness:

• It is defined as ability of the water to reduce surface tension property of the soap

• Hardness to water is of two types

• Temporary Hardness: It is caused by carbonates and bicarbonates which can be removed by boiling water.

• Permanent hardness: It is caused by sulphate and chloride of calcium and magnesium. It can be removed by using ion-exchange method

• Hard water leads to corrosion and incrustation in pipes

• Hard water makes the flood tasteless.

Chloride Content:

• Presence of chloride in high quantity indicates pollution of water due to sewage and industrial water.

Biological Parameters:

Total count of bacteria:

• In this total no of bacterial present in one milliliter of sample water are counted. The sample water is diluted. One milliliter is diluted in 99 ml of sterilized water.

• Then 1 ml diluted water is mixed with 10 ml of agar of gelatin in culture medium. This mixture is then kept in the incubator at 370c temperature for 34 hours.

• After that sample is taken out from the incubator then the colonies of bacteria are counted under microscope

• This no of colonies and dilution factor will give total number bacteria/ per ml of the undiluted water sample. Bacteria coli (B-coli) test of E coli test:

• Two tests are designed for B coli. The 1st test is know as presumptive test and 2nd test is known as confirmative test.

• Now a days an another method has been introduced to find out the B. coli. It is known as ‘membrane filter technique’

• Previously the standard statistical tables were referred to determine the most probable number (MP of B coli per 1000 ml.

• MPN indicates density of bacteria in the water sample. As new technique has been introduce the MPN methods are not used.