PREAMBLE

The Quality of drinking water in Chennai is monitored by Chennai Metropolitan Water Supply and Sewerage Board through the Quality Assurance Wing. The Quality of water is monitored through sampling, testing and reporting through the team of trained personnel in the laboratory. This division is headed by Executive Engineer and consists of Engineers and Analysts.

The Engineers of this wing provide the necessary Engineering service for effective functioning of the wing, preparation of reports, to take preventive actions at polluted water supply locations, and providing necessary assistance to the field staff in water quality surveillance.

The 10 Nos. of outsourced sample takers do the work of collecting water samples throughout Greater Chennai city, while the analysts analyse the water samples and report to the Engineers concerned in regard to whether the quality of water supplied to the public conforms to water quality standards. In addition to the outsourced sample takers, the Analysts also collect water samples throughout Greater Chennai City in specific locations, during monsoon season.

MONITORING WATER QUALITY

The scientific personnel in the Analytical section have a periodical sampling programme as per the W.H.O. norms, for monitoring water quality at the sources, treatment plants, Water distribution stations and in the distribution net work.

Water samples are being collected, once in a month from the lakes, which are the major source of water supply to the Chennai City. The treated water from the water treatment plants are collected from the test tap and samples were examined for conformity to physio-chemical and Bacteriological standards.

About 300 samples are tested from the City distribution system every day. The water samples are tested for physio-chemical parameters and bacteriological analysis. During monsoon period, the number of samples is doubled.

The water supplied to the public is assured as per norms laid down in BIS: 10500-2012, the Indian Standard. The Physical, Chemical and Bacteriological quality of water should not exceed the limits shown in the table below:

Sl.No.	Substance or Characteristic	Requirement (Acceptable Limit)	Permissible Limit
(i)	Colour	Colourless & Clear
(ii)	Odour	Agreeable	Agreeable
(iii)	Turbidity (N.T.U)	1	5
(iv)	Total Dissolved Solids at 105 0 C (mg/l)	500	2000
(v)	Calcium (As Ca) (mg/l)	75	200
(vi)	Magnesium (As Mg) (mg/l)	30	100
(vii)	Total Hardness (As CaCO3) (mg/l)	200	600
(viii)	Chlorides (As Caco3) (mg/l)	250	1000
(ix)	Ammoniacal Nitrogen (as N)(mg/l)	-	-
(x)	Albuminoid Nitrogen (as N)(mg/l)	-	-
(xi)	Nitrous Nitrogen (As N)(mg/l)	-	-
(xii)	Oxygen absorbed (Tidy's 4 hours test)(mg/l)	-	-
(xiii)	Hydrogen Ion Concentration (pH)	6.5 to 8.5	No Relaxation
(xiv)	Alkalinity to Phenolphthalein (AS CaCO3) (mg/l)	Nil	-
(xv)	Alkalinity to methyl orange (As CaCO3) (mg/l)	200	600
(xvi)	Sulphates (As SO4)(mg/l)	200	400
(xvii)	Phosphates (as PO4)(mg/l)	-	-
(xviii)	Iron (As Fe) (mg/l)	0.30	No Relaxation
(xix)	Florides (as F)(mg/l)	1.0	1.5
(xx)	Specific Conductance(micro Siemens /cm at 25o C)	-	-
(xxi)	Residual Chlorine (mg/l)	0.2	1.0
(xxii)	Nitrate (mg/l)	45	No Relaxation
(xxiii)	Bacterlological Quality MPN(Total Coliforms in 100 ml)	-	-

BACTERIOLOGICAL STANDARDS

I. Water entering the Distribution system

Coliform count in any sample of 100 ml should be Zero. A sample of the water entering the distribution system that does not conform to this standard, calls for an immediate investigation for both the efficacy of the purification process and the method of sampling.

II. Water in the distribution system

PRIVATE SAMPLES

Besides assuring the quality of water supplied by CMWSSB, the QA Wing facilitates the public within the limits of Greater Chennai Corporation (GCC) to assess the water quality of their own sources (Well / Bore Well water) by testing for Physio-Chemical examination on nominal charges as follows:

1.	Public (Individual houses-Drinking)	Rs.75/-	Per Sample
2.	Private Institute(Drinking)	Rs.200/-	Per Sample
3.	Private Institute(Construction)	Rs.200/-	Per Sample

The following parameters are tested for Physical and Chemical Examination for Drinking Purpose as per BIS 10500:2012.

Sl.No.	Parameters Name	BIS:10500-2012 ACCEPTABLE LIMIT	BIS:10500-2012 PERMISSIBLE LIMIT
(1)	Colour	Colourless & Clear	Colourless & Clear
(2)	Odour	Agreeable	Agreeable
(3)	Turbidity (N.T.U)	1	5
(4)	Total Dissolved Solids at 105'C(mg/l)	500	2000
(5)	Calcium (As Ca) (mg/l)	75	200
(6)	Magnesium (As Mg) (mg/l)	30	100
(7)	Total Hardness (As CaCO3)(mg/l)	200	600
(8)	Chlorides (As Cl) (mg/l)	250	1000
(9)	Ammoniacal Nitrogen (as N) (mg/l)	-	-
(10)	Albuminoid Nitrogen (as N) (mg/l)	-	-
(11)	Nitrous Nitrogen (as N) (mg/l)	-	-
(12)	Oxygen absorbed (Tidy's 4 hours test) (mg/l)	-	-
(13)	Hydrogen Ion Concentration (pH)	6.5 to 8.5	No Relaxation
(14)	Alkalinity to Phenolphthalein (AS CaCO3)(mg/l)	Nil	-
(15)	Alkalinity to methyl orange (As CaCO3)(mg/l)	200	600
(16)	Sulphates (As SO4) (mg/l)	200	400
(17)	Phosphates (as PO4) (mg/l)	-	-
(18)	Iron (As Fe) (mg/l)	0.3	No Relaxation
(19)	Fluorides (as F) (mg/l)	1.00	1.5
(20)	Specific Conductance (micro Siemens/cm)at 25'c	-	-
(21)	Residual Chlorine (Cl2)	0.2	1.0

The QA Wing facilitates the public within the limits of Greater Chennai Corporation (GCC) to assess the water quality of their own sources for its suitability for Construction purpose.

Water used for mixing and curing shall be clean and free from injurious elements like oils, acids, alkalis, salts, sugar, organic materials or other substances that may be deleterious to concrete or steel.

Permissible Limit for Solids for Construction purposes - IS 456 : 2000

Sl.No	Name of the parameter	IS:456-2000 Permissible Limit
1.	Colour	-
2.	Odour	-
3.	Turbidity (N.TU)	-
4.	Chlorides (As Cl) (mg/l)	2000
5.	Hydrogen Ion Concentration (pH)	Not less than 6.0
6.	Sulphates (As SO4) (mg/l)	400
7.	Iron (As Fe) (mg/l)	Nil
8.	Ignited Residue (mg/l)	3000
9.	Organic Solids (mg/l)	200
10.	Requirement of 0.02 N H2SO4 to neutralise 100 ml sample (ml)	25 ml
11.	Requirement of 0.02 N NaOH to neutralise 100 ml sample (ml)	5 ml

Quantity of samples required for testing are as follows:

Drinking Purpose:	2 litres
Construction Purpose:	5 litres

The containers used for collecting water samples should be free from any contamination. It is advised to use new plastic container of required capacity as mentioned above.