ANDRES Water Quality Parameters ENE 127

Water Quality Parameters
Water quality testing is an important part of environmental monitoring. When water

quality is poor, it affects not only aquatic life but the surrounding ecosystem as well. These
sections detail all of the parameters that affect the quality of water in the environment. There
are three types of water quality parameters physical, chemical, and biological.
1. Physical parameters of water quality
a. Turbidity
Turbidity is the cloudiness of water. It is a measure of the ability of light to pass through
water. Turbidity in drinking water is esthetically unacceptable, which makes the water look
unappetizing. Some impact of turbidity includes the following:
• It can increase the cost of water treatment for various uses
• The particulates can provide hiding places for harmful microorganisms and
thereby shield them from the disinfection process
• Suspended materials can clog or damage fish gills, decreasing its resistance to
diseases, reducing its growth rates and affecting the efficiency of fish catching
method.
b. Temperature
The temperature of water affects some of the important physical properties and
characteristics of waters such as thermal capacity, density, specific weight, viscosity, surface
tension, salinity, and solubility of dissolved gases. Chemical and biological reaction rates
increase with increasing temperature.
c. Color
Color is measured by comparing the water sample with standard color solutions or
colored glass disks. Colored water gives the appearance of being unfitted to drink even though
the water may be perfectly safe for public use. On the other hand, color can indicate the
presence of organic substances such as algae or humic compounds.
d. Taste and Odor
Days in order are human perceptions of water quality. Taste and odor in water can be
caused by foreign matter such as organic materials, inorganic compounds, or dissolved gasses.
e. Solids
The total solids content of water is defined as the residue remaining after evaporation of the
water and dying the residue to a constant weight at 100-105 degrees Celsius.
2. Chemical parameters of water quality
a. pH
pH is one of the most important parameters of water quality. It is defined as the negative
logarithm of the hydrogen ion concentration. It is a dimensionless number indicating the
strength of an acidic or a basic solution. Actually, pH of water is a measure of how
acidic/basic water is.
b. Acidity
Acidity is the measure of acids in a solution. The acidity of water is its quantitative
capacity to neutralize a strong base to a selected pH level. Acidity in water is usually due to
carbon dioxide, mineral acids, and hydrolyzed salts such as ferric and aluminum sulfates.
c. Chloride
Chloride occurs naturally in groundwater, streams, and lakes, but the presence of
relatively high chloride concentration in freshwater (about 250 mg/L or more) may indicate
wastewater pollution. Chloride ions Cl− in drinking water do not cause any harmful effects on
public health, but high concentrations can cause an unpleasant salty taste for most people.
Chlorides are not usually harmful to people; however, the sodium part of table salt has been
connected to kidney and heart diseases.
d. Conductivity
The concentration of total dissolved solids is related to electrical conductivity or specific
conductance the conductivity measures the capacity of water to transmit electrical current TDs
and conductivity affect the water sample and the solubility of slightly soluble compounds and
gases in water.
e. Biological Oxygen Demand
Biological oxygen demands the most widely used parameter is a measure of the amount
of oxygen used by indigenous microbial population in water in response to the introduction of
degradable organic material this parameter depends on water characteristics such as dilution
essential nutrients and bacteria seed.
f. Chemical Oxygen Demand
The chemical oxygen demand test of natural water yields the oxygen equivalent of the
organic matter that can be oxidized by strong chemical oxidizing agent in acidic medium.
g. Radioactive Substances
Potential sources of radioactive substances in water include wastes from nuclear power
plants, industries, or medical research using radioactive chemicals and mining of uranium ores
or other radioactive materials. When radioactive substances decay, they release beta, alpha, and
gamma radiation. Exposure of humans and other living things to radiation can cause genetic
and somatic damage to the living tissues.
h. Dissolved Oxygen
Dissolved oxygen (DO) is considered to be one of the most important parameters of
water quality in streams, rivers, and lakes. It is a key test of water pollution. The higher the
concentration of dissolved oxygen, the better the water quality.
3. Biological parameters of water quality
a. Bacteria
Bacteria are considered to be single-celled plants because of their cell structure and the way
they ingest food. This rapid growth of visible colonies of bacteria on a suitable nutrient medium
makes it possible to detect and count the number of bacteria in water.
b. Algae
Algae are microscopic plants, which contain photosynthetic pigments, such as chlorophyll.
They are important for wastewater treatment in stabilization ponds. Algae are primarily
nuisance organisms in the water supply because of the taste and odor problems they create.
c. Viruses
Viruses are the smallest biological structures known to contain all genetic information
necessary for their own reproduction. Viruses are parasites that need a host to live. They can
pass through filters that do not permit the passage of bacteria. Most of the waterborne viruses
can be deactivated by the disinfection process conducted in the water treatment plant.
d. Indicator organisms
A very important biological indicator of water and pollution is the group of bacteria called
coliforms. Pathogenic coliforms always exist in the intestinal system of humans, and millions
are excreted with body wastes. Consequently, water that has been recently contaminated with
sewage will always contain coliforms.
e. Protozoa
Aquatic protozoa are floating freely in water and sometimes called zooplankton. They form
cysts that are difficult to inactivate by disinfection.
f. Testing for coliforms: member filter method
A measured volume of sample is filtered through a special membrane filter by applying a
partial vacuum. The filter, a flat paper-like disk, has uniform microscopic pores small enough
to retain the bacteria on its surface while allowing the water to pass through. The filter paper
is then placed in a sterile container called a petri dish, which contains a special culture medium
that the bacteria use as a food source.

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Water Quality Parameters

Water quality testing is an important part of environmental monitoring. When water

1. Physical parameters of water quality

3. Biological parameters of water quality

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