Water Quality Monitoring

by
Manoj Kumar
What is Water Quality?
“Water quality” is a term used to express the suitability of water to sustain
various uses or processes.
Any particular use will have certain requirements for the physical, chemical
or biological characteristics of water. So, water quality can be defined by a
range of variables which limit water use.
Water quality is measured by several factors, such as the concentration of
dissolved oxygen, bacteria levels, the amount of salt (or salinity), or the
amount of material suspended in the water (turbidity).
In some bodies of water, the concentration of microscopic algae and
quantities of pesticides, herbicides, heavy metals, and other
contaminants may also be measured to determine water quality.
What’s Affecting Water Quality?
Water quality is affected by a wide range of natural and human influences.
The most important of the natural influences are:
• Geological
• hydrological
• climatic
These affect the quantity and the quality of water available.
Their influence is generally greatest when available water quantities are low
and maximum use must be made of the limited resource; for example, high
salinity is a frequent problem in arid and coastal areas.
If the financial and technical resources are available, seawater or saline groundwater
can be desalinated but in many circumstances this is not feasible.
Thus, although water may be available in adequate quantities, its unsuitable quality
limits the uses that can be made of it.
CONT.
The effects of human activities on water quality are both widespread and varied
in the degree to which they disrupt the ecosystem and/or restrict water use.
For Example:
• Human faeces pollution in water bodies.
• Eutrophication (High nutrient concentration in water bodies).
Pollution from diffuse sources, such as agricultural runoff, or from numerous small
inputs over a wide area, such as faecal pollution from unsewered settlements, is
particularly difficult to control.
CONT.
• Human activities can modify water quality in two ways.
1. First, water quality is changed when we add pollutants like:
 nutrients from fertilizer and animal waste,
 heat from paved surfaces and industrial processes,
 faecal bacteria from sewage, farm animals, pets,
 industrial chemicals,
 heavy metals (includes lead, mercury, and cadmium from industrial sources, mining, and
smelting),
 oil and gasoline etc.
2. The second way we impact water quality is by changing ecological
processes that naturally purify water.
https://www.change.org/p/hon-rble-prime-minister-of-india-do-you-know-yamuna-
river-does-not-flow-in-braj-vrindavan-any-more-please-keep-you-words-from-mar-21-
2015-declaration-http-saveyamuna-org-21mar2015.
https://www.hindustantimes.com/photos/india-news/river-
yamuna-a-day-after-durga-puja/photo-
77zTIMDmfLWZ56KL3UsU6N.html (2016).
https://economictimes.indiatimes.com/news/politics-and-nation/delhi-pollution-devotees-stand-
knee-deep-in-toxic-foam-in-yamuna-for-chhath-puja/toxic-yamuna
water/slideshow/71888429.cms (2019).
Major Concern

Water
Pollution

Loss of Loss of
Ecosystem Biodiversity
Change in
water quality

Disruption
Diseases of Food
chain
Effect of Water Pollution; Case Study
• Human activities, especially agriculture, have led to large increases in the levels of
nitrogen and phosphorus in the Water which causes eutrophication (excessive growth of
phytoplankton and algae). Consequence of this is Harmful algal blooms—blooms of species
that produce deadly toxins and sometimes known as “red tides” or “brown tides” for
their appearance in the water—can kill fish, marine mammals and seabirds and harm
humans.
• Pollution can poison water bodies and can make “Dead Zones”. Dead zone also can be
formed when blooms eventually die off because of nutrient depletion, bacteria may suck up
all the oxygen from the water as the algae decompose. This hypoxia creates a “dead zone”
where fish cannot live.
• More than 400 areas around the world have been identified as experiencing eutrophication
and 169 are hypoxic. polluted water pours down the Mississippi River, poisoning the water
in the Gulf of Mexico and causing an 8,000-square-mile dead zone — is an example.
https://swachhindia.ndtv.com/yamuna-pollution-dead-fish-
mathura-ghats-raise-pollution-alarm-27472/ (2018)
https://www.pinterest.com/pin/281686151680719500/
 What is Water Quality Monitoring?
Monitoring is defined by the International Organization for Standardization
(ISO) as: “the programmed process of sampling, measurement and subsequent
recording or signalling, or both, of various water characteristics, often with the
aim of assessing conformity to specified objectives”.
This general definition can be differentiated into three types of monitoring
activities that distinguish between long-term, short-term and continuous
monitoring programmes as follows:
Monitoring is the long-term, standardised measurement and observation of the
aquatic environment in order to define status and trends.
Surveys are finite duration, intensive programmes to measure and observe the
quality of the aquatic environment for a specific purpose.
Surveillance is continuous, specific measurement and observation for the purpose
of water quality management and operational activities.
Purpose of Water Quality Monitoring
The principal reason for monitoring water quality is:
• to verify whether the observed water quality is suitable for intended uses.
• to determine trends in the quality of the aquatic environment and how the
environment is affected by the release of contaminants.
• to estimate nutrient or pollutant fluxes discharged by rivers or ground waters to
lakes and oceans.
• Monitoring for background quality of the aquatic environment.
Designing of a Monitoring Programme
The principal elements of a study plan are:

a clear statement of aims and objectives,

information expectations and intended uses,

a description of the sampling sites,

a listing of the water quality variables that will be measured,

proposed frequency and timing of sampling,

an estimate of the resources required to implement the design.

1. Defining the objective of water quality Monitoring.
Some common objectives of water quality monitoring is:

• Identification of baseline conditions in the water-course system. Detection of any

signs of deterioration in water quality.

• Identification of any contaminated areas.

• Determination of the extent and effects of specific waste discharges.

• Development of water quality guidelines and/or standards for specific water

uses.

• Development of a water pollution control programme.

2. Sampling.

Sampling must be done in clean sample bottles by following all the precautions.

Generally occurred in three steps:

(a) Selecting sampling site:

• A sampling site is the general area of a water body from which samples are to be taken
and is sometimes called a “macrolocation”.

(b) Selecting sampling station:

• The exact place at which the sample is taken is commonly referred to as a sampling
station or, sometimes, a “microlocation”.

(c) Sampling:

• Sampling can be Grab sampling, Composite sampling or Integrated sampling.

https://www.slideshare.net/praveenvatsh/water-sampling-
methods-and-tools
3. Monitoring different parameters of water quality.
In this step, analyses for many important physical, chemical and microbiological
variables can be carried out.

It can be done in two ways:

(a) At field level: different parameters like Temperature, pH, Transparency,

Conductivity (specific conductance), Dissolved Oxygen are done at field.

(b) At laboratory level: BOD, COD, Phosphate, Nitrate, Alkalinity, Acidity etc. should
be checked at laboratory.
Key Indicators of Water Quality
Water quality indicators Analysis can be divided into 3 types:

(i) Physical indicators

(ii) Chemical indicators

(iii) Biological indicators

• Analysis of these indicators show the quality of water and define its use.

• Different organizations (international or national) give standards for these

indicators. The standards depends on the use of water.
Physical Indicators
Temperature
• Temperature must be measured in field because a water sample will gradually reach
the same temperature as the surrounding air.
• Temperature influences several parameters and can alter the physical and chemical
properties of water.

Transparency
• This characteristic varies with the combined effects of colour and turbidity.
• This could be observed by naked eye.
pH
• The pH of a solution is the concentration of hydrogen ions, expressed as a negative
logarithm
• The pH of natural water lies between 4-9. Water is slightly basic due to the presence
of HCo3-, Co32- ions.

Conductivity (or specific conductance)

• Electrical conductivity is the measure of the ability of water to conduct an electric
current and depends upon the number of ions or charged particles in the water.
• Water conducts electricity due to the presence of dissolved ions in it.
Chemical Indicators
Dissolved Oxygen (DO)
• Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in an
aqueous solution.
• Dissolve Oxygen (DO) levels in natural and wastewater depend on the physical, chemical and
biochemical activities in the water body and it is the key test in water pollution and waste
treatment process control.
• The standard range of DO in Inland surface water is 4 – 6 mg/l.

Biological oxygen demand (BOD)

• Amount of oxygen used by micro-organisms to degrade oxidizable organic matter is
know as BOD.
• The BOD is used as an approximate measure of the amount of biochemically degradable
organic matter present in a sample.
• The standard range of BOD in Inland surface water is 30 mg/l.
Chemical oxygen demand (COD)
• COD is the measurement of the amount of oxygen in water consumed for chemical
oxidation of pollutants.
• It does not differentiate between biologically available and inert organic matter.
• The test is relatively easy, precise, and it takes less time than BOD.
• COD values are always greater than BOD values.
• The standard range of COD in Inland surface water is 250 mg/l.

Nitrate
• Nitrate is an essential plant nutrient and its levels in natural waterways are typically low
(less than 1 mg/L).
• Significant sources of nitrate are chemical fertilisers from cultivated land and drainage from
livestock feedlots, as well as domestic and some industrial waters.
• Nitrate is a nutrient taken up by plants and converted into cell protein. The growth
stimulation of plants, especially of algae may cause eutrophication.
• The standard range of Nitrate in Inland surface water is 10 mg/l.
Phosphorus
• Phosphorus occurs in natural waters and in wastewaters almost solely as phosphates.
• Sources of phosphorus enrichment may include some detergents, fertilizers, animal
faeces.
• The presence of phosphate in large quantities in fresh waters indicates pollution through
sewage and industrial wastes.
• The standard range of Phosphate in Inland surface water is 5mg/l.

Sulphate
• Sulphate is an abundant ion in the earth’s crust and its concentration in water can range
from a few milligrams to several thousand milligrams per litre.
• Sulphate cause scaling in water supplies, and problem of odour and corrosion in wastewater
treatment due to its reduction to H2S.
• catharsis, dehydration and gastrointestinal irritation have been observed at high
concentrations of sulphate in drinking water.
• The recommended concentration of sulphate in drinking water is 500mg/l.
Microbiological Indicators
• Microbial analysis of water is required to overcome the problems with waterborne
diseases and water quality monitoring.
• Faecal contamination of water is assessed and the concept relies on the fact that
certain non-pathogenic bacteria present in water can be easily isolated and
quantified by simple bacteriological methods.
• Detection of these bacteria would essentially mean that faecal contamination has
occurred and also suggest that enteric pathogens also may be present.
• Total coliform count and faecal coliform count is done to calculate the number of
microbes present in water.
• Most recommended method of microbiological analysis by WHO is Most probable
number (MPN) method.
• Recommended number of microbes in inland surface water is 103 cells/ml.
How to prevent water quality depletion?
Role of Government:
• Govt. should make strict laws to prevent water pollution by industries and locals.
• Fund the programmes to clean water sources and to increase awareness in public.

Role of an individual:
• Don’t throw waste in water bodies or in open. Use proper bins.
• Use water wisely and do not waste clean water.
• Buy more environment safe chemicals and pesticides etc. Prevent the use of harmful
pesticides as much as possible.
• Follow the proper protocols and laws made by govt. to reduce pollution.
Role of Industries
• Follow proper waste disposal protocols made by govt. and other agencies.
• Use sewage treatment plants to clean the waste water produced during production
processes and reuse it.
• Do not dispose the waste before processing and follow disposal guidelines.
References
1. https://apps.who.int/iris/bitstream/handle/10665/41851/0419217304_eng.pdf;
jsessionid=7FDEA9E4A31E2C4FCF4397B15017035E?sequence=1
2. http://www.longwood.edu/cleanva/images/Sec5.WQMchapter.pdf
3. https://eschooltoday.com/pollution/water-pollution/prevention-of-water-
pollution.html
4. https://www.nrdc.org/stories/water-pollution-everything-you-need-
know#effects
5. https://homeguides.sfgate.com/can-water-pollution-affect-animals-homes-health-
79201.html
6. https://www.worldwildlife.org/threats/pollution
Thank You