Water has three characteristics, i.e. physical, chemical, and biological characteristics. The uncooked treated water may be checked and analyzed through analyzing and checking out these CHARACTERISTIC OF WATER as defined below:


a)Turbidity:- If a large amount of suspended matter such as clay, silt, or other organic material is present in water it will appear to be muddy or turbid in appearance.

  • Amt of suspends matter. Unit-ppm or JTV or NTV


i) field – Turbidity Rod, Lab (i) Jackson’s turbidity meter – candle test.

Longer the light path – lower the turbidity 10.8cm ≈200JTV

Can’t measure Turbidity less than 25JTV

(ii) Nephelometer- Light reflection test Can measure Turbidity less than 1ppm

NTV (unit )= Nephelomete Turbidity unit

PLD (Permissible limit for drinking water) = 5 to 10 limit

b) Colour:- Measured in “ Burgress scale” with Nessler tubes or colour scale”. The more precise instrument is –Tintometer

PLD (Permissible limit for drinking water) on cobalt scale = 5 to 10 limit

c) Taste & Odour:- Taste and odour may be caused by the presence of dissolved gases such as H2S, CH4, CO2 etc. combined with organic matter Test A ml of odour sample +B ml of a dilute sampleA+B=200ml.

  • Amt of suspends matter. Unit-ppm or JTV or NTV

 Threshold \:\: Odor\: Number = \frac{A+B}{A}

PLD (Permissible limit for drinking water) = it should not exceed 3

d) Temperature:-

PLD (Permissible limit for drinking water) = 100c should never exceed 250


a) Total solid and suspended solids- Total solid measured by evaporation, the suspended solids can be found by filtering the water sample and weighing the residue left on the filter paper. The difference between total solid and suspended solid gives the dissolved solids

Dissolved solid =Total solid –suspended solid.

PLD(Permissible limit for drinking water)=500ppm

 (b)\: pH=\: -\log{[H^+]}  P^{OH}=-log_{10}[OH]  [H^{+}][OH] = 10^{14}

 P^H + P^{OH} = 14

The lower value of it (acidic) may cause corrosion and the higher value of it (alkaline) may produce incrustation.

Measurement is done by potentiometer or by colour indicator generally 2 indicators used are
Methyl orange→(2.8-4.4), the original colour is red, finally converted to yellow
Phenolphthalein→(8.6-10.3 ), the original colour is yellow, finally converted to red

PLD(Permissible limit for drinking water)=6.6 to 8.5

c) Hardness:- If carbonate and bicarbonate of & mg present called temperature. hardness, sulfate, carbonate, and nitrate present called permanent hardness.

  • Carbonate hardness→It is equal to total hardness or alkalinity whichever is less
  • Non-carbonate →only presents if Total hardness is more than Alkalinity.


Major sources → CO3, HCO3−, OH−

 (a)\: Equivalent\: weight = \frac{molecular\: weight}{valency}

 Equivalent\: weight \:of\: CaCO_{3}= \frac{40+212+3*16}{2}= 50

 Gram\:equivalent\: number \:of\: equivalent= \frac{\omega t}{equivalent\:\omega t}

PLD (75-115)PPm

Measurement by titration using EDTA also called ‘versanate’ solution.

 [ca^{2^+}\: * \: \frac{combining \: wt\: of\: caco_3}{combining \: wt\: of\: ca^{2^+}} ] \:+\:[ mg^{2^+} \:*\: \frac{combining \: wt\: of\: caco_3}{combining \: wt\: of\: mg^{2^+}} ]

Combining wt. of, ca, mg & caco3are 20, 12, 50 respectively.

(d) Chloride content:– A large amount of chloride may enter from industries. Nacl present in the form.

PLD = 250

Test – Titration with silver nitrate using KMO4 indicator.

(e) Nitrogen content:- It gives the indication of the presence of organic matter may present in any form.

(i) Free Ammonia- Indicates the first stage of decomposition of organic matter or gives the indication of recent pollution
(ii) Organic Nitrogen (Albuminoid)- Indicates the amount of nitrogen found in the water earlier than the decomposition of natural remember is started.
(iii) Nitrites– Indicates the presence of partially decomposed organic matter.
(iv) Nitrates- Indicates the presence of fully oxidized organic matter.
—> Excess of nitrate may cause Methemoglobinemia or blue baby disease
—> Free Ammonia & org. Nitrogen called ‘Kjeldahl Nitrogen

PLD Ammonia =0.15, org. Nitrogen =0.3 Nitrite =zero, Nitrate = 45ppm

(f) PLD of other chemicals

(a) Mn= 0.05ppm

(b) Fluoride= (1-1.5)ppm, <1 cause –tooth decay >1.5cause →spotting of teeth

(c) Iron =0.3ppm

(d) Sulphate =250ppm

(g) BOD (Bio chemical oxygen demand):- BOD of water during 5 days at 20 degree Celsius is generally taken as the std. demand required. It’s a demand by Microorganism for the degradation of organic matter.


BOD 5day at 200 c= [(D. O)i − (D. O)f] * Dilution factor

  • Condition (D. o)i should ≮ 1ppm, (D. o)f should not more then 7ppm


The rate at which BOD is satisfied at any time depends upon temp and also on the amount and nature of organic matter present in water at any time. It can be calculated using:

h) C.O.D:- Potassium dichromate (K2Cr2O7 )or Potassium permanganate (KMn04 ) which are oxidizing agents are used to destroy the organic matter. As organic matter is of two types biologically degradable and non-biodegradable.


Most bacteria are harmless, and under certain conditions beneficial to human beings, animals and crops. Such bacteria or micro-organisms are called non-pathogenic bacteria or non-pathogens. Certain other bacteria are dangerous for and may cause serious water-borne diseases, such as cholera, typhoid, infectious hepatitis, etc. such dangerous micro organism or organisms are referred to as pathogenic micro organism or pathogens.

(i) Aerobic- Oxygen is required for Survival

(ii)Anaerobic- Don’t require oxygen for survival

(iii)Facultative- can survive with O2 or without O2

→Test by counting of Coliforms (harmless Aerobic m.o) found residing in the intestines of all warm-blooded animals including human beings.
→life of coliform is higher than pathogenic bacteria, hence if no coliform present water will be safe and free from pathogen.

PLD 1coliform per 100ml of Water

→Determine using MPN (most probable number) test- By mixing different samples of water with lactose and incubating them with test tubes for48 hr. The presence of acid or co2 in the test tube will indicate the presence of coliform bacteria, then referring to std. statistical tables the MPN of b.coli per 100ml of water can be found.
→It can also be determined by the membrane filter technique.

Diseases caused by Bacteria
a)Typhoid- caused by Salmonella Typhi (Bacteria, b)Cholera- caused by Vibrio – cholera, c)Bacillary dysentery – caused by Shiga bacillus.

Diseases caused by a viral infection
(i) Hepatitis (infectious jaundice)– caused by the Hepatitis virus
(ii) Poliomyelitis– caused by Poliovirus



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