Drinking Water Testing & Analysis

Drinking Water Testing & Analysis in Laboratory is necessary for Human health. We test Total Coliform Bacteria, Nitrate, pH, Hardness and TDS in Our Lab.

We put a lot of trust when we draw water from tap for a variety of different purposes like drinking, bathing, cooking, etc. Don’t we? We are able to do that knowing that the water provided to us is treated and tested.

Water testing helps us out to know if the water is safe for usage or not.

What is Water Quality Testing?

Water Quality Testing is a broad description for various procedures used to analyse water quality. Different parameters are analysed for testing the quality of water to ensure if water is safe for usage.

Water testing is just not limited to testing of drinking water. It also plays a major role in testing of domestic waste water, industrial effluents, packaged/natural mineral water, ground water, etc.

Need of Drinking Water Analysis

We have around 60% water in our body. i.e 2/3 rd part of human body is made up of water. what if the water we are drinking is contaminated? Over 3 million people die (majorly because of Diarrhea) every year due to consumption of contaminated water. To make sure that water we are drinking is pure and contains no bacteria and harmful metals Drinking water analysis in Laboratory is necessary. We have heard precaution is better than cure since our childhood it is true in this case also.

Let’s imagine a scenario where water sent to us is not being tested. It may happen that the water might contain biological contaminants which may cause health problems.

Or

Let’s imagine another scenario where water discharged from industries is directly released into open sources of water without being tested. It may happen the water being discharged has high levels of Chromium, Nitrates, Phosphates or biological contaminants which can have a serious impact on aquatic ecosystem leading to its destruction.

This helps us understand the level of threat that lies if water is used or discharged without testing? Regular practice of water testing rules out the chances of suffering from health problems and also gives us a chance to protect our precious environment.

Location of Drinking Water Sampling Points

Drinking water Sampling is most important process in Drinking water analysis. it must be taken from location that is representative of water source to be tested.

Sampling Frequency

The Most important test in water quality surveillance are those for microbiological quality i.e. indicator of bacteria, Turbidity, Free chlorine, pH. These should be carried out whenever a sample is taken. It is recommended that drinking water analysis to be carried out once in a year.

Storage of Samples

Although recommendation varies, the time between sample collection & analysis should, in general not exceed 6 hours, whereras 24 Hours is considered to be the absolute maximum. It is assumed that the samples are immediately placed in a light proof insulated box containing melting ice or ice packs with rapid cooling. If ice is not available, the transportation time must not exceed 2 hours before drinking water analysis.

Having understood the importance of testing water quality, the next question arises is how to test water quality.

Testing and Analysis of Water Quality

For water quality testing it is necessary to first understand the purpose; where the water is going. Will it be used for drinking purposes or will the water be discharged into open sources. Once this is known then the standards and parameters which need to be analysed should be understood.

  • Standards

Some of the standards which are usually referred during Analysis of Water quality are of APHA, IS, CPCB and WHO. Depending upon the purpose, the set of standards can be referred.

  • Types of tests

Water testing can be grouped into three major categories.

  • Physical Tests For Water Quality – These indicate properties which are detectable by senses.Colour, Turbidity, Odour and Taste, these parameters are grouped under physical tests.
  • Chemical Tests for Water Quality – These determine the amount of mineral and organic substances that affect the quality of water. pH, BOD, DO, Ca, Mg, Cl are some of the parameters which are grouped under chemical tests.
  • Bacteriological Tests for Water Quality – These indicate the presence of bacteria. Bacteriological tests are used primarily as an indicator of faecal contamination.

Sampling Methods for Physio-Chemical Analysis In Laboratory

Result of physio-chemical analysis is of no value if the sample tested are not properly collected & stored. In general, Time between sampling & analysis should be kept to a minimum. Storage in a glass or polyethylene bottles at low temperature (e.g. 4 DegC) in the dark is recommended. pH, Turbidity & Residual chlorine should be tested immediately after sampling as they will chance during storage & transportation.

Physico-Chemical Analysis in Laboratory

Chlorine residual

The disinfection of drinking-water supplies constitutes an important barrier against waterborne diseases. Although various disinfectants may be used, chlorine in one form or another is the principal disinfecting agent employed in small communities in most countries. Three types of chlorine residual may be measured: free chlorine (the most reactive species, i.e. hypochlorous acid and the hypochlorite ion); combined chlorine (less reactive but more persistent species formed by the reaction of free chlorine species with organic material and ammonia); and total chlorine (the sum of the free and combined chlorine residuals).

pH

Portable pH electrodes and meters are available. If these are used in the laboratory, they must be calibrated against fresh pH standards at least daily; for field use, they should be calibrated immediately before each test. Results may be inaccurate if the water has a low buffering capacity and it will not serve the purpose of drinking water analysis.

Turbidity

In all processes in which disinfection is used, the turbidity must always be low—preferably below 1 NTU. It is recommended that, for water to be disinfected, the turbidity should be consistently less than 5 NTU.

Color

If Drinking water is colored then may be colored organic matter, e.g. humic substances, metals such as iron and manganese, or highly colored industrial wastes are present. Drinking-water should be colorless.

Taste and Odour

Odors in water are caused mainly by the presence of organic substances. Some odors are indicative of increased biological activity, others may result from industrial pollution. Generally, the taste buds in the oral cavity detect the inorganic compounds of metals such as magnesium, calcium, sodium, copper, iron, and zinc. As water should be free of objectionable taste and odor, it should not be offensive to the majority of the consumers.

Drinking Water Parameters and Standards to be checked in Laboratory

Water is a vital natural resource which is essential for multiplicity of purpose. Drinking water quality standards describes the quality parameters set for drinking water. Drinking water or potable water is water safe enough to be consumed by humans. In most developed countries, the water supplied to households, commerce and industry meets drinking water quality standards, even though only a very small proportion is actually consumed or used in food preparation. Typical uses (for other than potable purposes) include toilet flushing, washing and landscape irrigation.

As Per Indian Standard Specifications For Drinking Water Quality standards:


Sr No.
Parameter
Limits as per Is
10500:2012
Unit(s)
Standard Method
1.
Color
5
Hazen
IS : 3025 (Part 4):1983
2.
Odour
Agreeable
--
IS : 3025 (Part 5):1983
3.
Taste
Agreeable
--
IS : 3025 (Part 7 and 8):1984
4.
Turbidity
1
NTU
IS : 3025 (Part 10):1984
5.
TDS
500
ppm
IS : 3025 (Part 16):1984
6.
pH
6.5 to 8.5
--
IS :3025 (Part 11)1984
7.
Total Hardness
200
mg/lit
IS : 3025 (Part 21)1983
8.
Total Alkalinity as calcium carbonate
200
mg/lit
IS : 3025 (Part 13)1964
9.
Sulphate
200
mg/lit
IS : 3025 (Part 24)1986
10.
Nitrate
45
mg/lit
IS : 3025 (Part 34)1988
11.
Fluoride
1.0
mg/lit
IS : 3025 (Part 23)1983
12.
Residual Chlorine
0.20
mg/lit
IS : 3025 (Part 26)1986
13.
Chloride
250
mg/lit
IS : 3025 (Part 32)1988
14.
Phenolic compounds
0.001
mg/lit
IS:3025(Part 43)
15.
Calcium (as Ca)
75
mg/lit
IS : 3025 (Part 40)1991
16.
Magnesium (as Mg)
100
mg/lit
IS : 3025 (Part 46)
17.
Total Ammonia
0.5
mg/lit
IS : 3025 (Part 34)1988
18.
Chloramines as Cl2
4.0
mg/lit
IS : 3025 (Part 26)
19.
Mineral Oil
0.5
mg/lit
IS: 3025(Part 39):1991
20.
Sulphide
0.05
mg/lit
IS: 3025(Part 29):1986
21.
Cyanide
0.05
mg/lit
IS: 3025(Part 39):1991
22.
Anionic detergents as MBAS
0.2
mg/lit
Annex K of IS 13428
23.
Iron as Fe
0.3
mg/lit
AAS Method
24.
Copper as Cu
0.05
mg/lit
AAS Method
25.
Mercury as Hg
0.001
mg/lit
AAS Method
26.
Cadmium as Cd
0.03
mg/lit
AAS Method
27.
Selenium as Se
0.01
mg/lit
AAS Method
28.
Arsenic as As
0.01
mg/lit
AAS Method
29.
Lead as Pb
0.01
mg/lit
AAS Method
30.
Zinc as Zn
5
mg/lit
AAS Method
31.
Aluminum as Al
0.03
mg/lit
AAS Method
32.
Boron as B
1.0
mg/lit
AAS Method
33.
Silver
0.10
mg/lit
AAS Method
34.
Molybdenum
0.07
mg/lit
AAS Method
35.
Nickel
0.02
mg/lit
AAS Method
36.
Barium
0.70
mg/lit
AAS Method
37
Manganese
0.10
mg/lit
AAS Method
38.
chromium
0.05
mg/lit
AAS Method
39.
2,4-Dichlorophenoxy acetic Acid
0.01
µg/L
SO-IN-MUL-TE-023
40.
Alachlor
0.01
µg/L
SO-IN-MUL-TE-023
41.
Aldrin/Dleldrin
0.01
µg/L
SO-IN-MUL-TE-023
42.
Alpha HCH
0.01
µg/L
SO-IN-MUL-TE-023
43.
Beta HCH
0.01
µg/L
SO-IN-MUL-TE-023
44.
Delta HCH
0.01
µg/L
SO-IN-MUL-TE-023
45.
DDT (o,p and p,p-isomers of DDT,DDE and DDD) Gamma HCH (Lindane)
0.01
µg/L
SO-IN-MUL-TE-023
46.
Atrazine
2.0
µg/L
525.2
47.
Butachlor
0.01
µg/L
SO-IN-MUL-TE-023
48.
Chloropyriphos
30.0
525.2
49.
Endosulfan (alpha,beta,& sulphate)
0.01
µg/L
SO-IN-MUL-TE-023
50.
Gamma HCH
2.0
µg/L
508
51.
Ethicon
3.0
µg/L
1657 A
52.
Isoproturon
9.0
µg/L
532
53.
Malathion
190.0
µg/L
8141 A
54.
Methyl Parathion
0.3
µg/L
8141 A
55.
Monocrotophos
1.0
µg/L
8141 A
56.
Phorate
2.0
µg/L
8141 A
58.
Bromoform
0.1
µg/L
ASTM D 3973-85
59.
Chloroform
0.2
µg/L
ASTM D 3973-85
60.
Dibromochloromethane
0.1
µg/L
ASTM D 3973-85
61.
Bromodichloromethane
0.06
µg/L
ASTM D 3973-85
62.
Total Coliform
Absent
MPN/100ml
IS 1622:1981
63.
E.coli.
Absent
Per 100ml
IS 1622:1981


These are some of the common parameters analyzed to test the water quality.