Water Quality
What is Water Quality?
Water quality can often be defined in terms of the chemical, physical, and biological content of water. The water quality of rivers and lakes changes with the seasons and geographic areas, even when there is no pollution present.
It 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.
Therefore, water quality describes a broad spectrum of items related to how we identify water concerns and how we collectively address them.
The Importance of Water Quality
Water quality is important as it directly affects the health of the people, animals, and plants that drink or otherwise utilize the water. When water quality is compromised, its usage puts users at risk of developing health complications. The environment also suffers when the quality of water is low. The availability of high-quality water is a key determinant for human, animal and plant survival.
Also, water quality monitoring can help predict and learn from natural processes in the environment and determine human impacts on an ecosystem. These measurement efforts can also assist in restoration projects or ensure environmental standards are being met.
Water Quality Instruments at Gaafu Dhaalu Atoll Education Centre, Thinadhoo
The Thinadhdhoo School (Gaafu Dhaalu Atoll Education Centre) has been provided with water quality instruments for the students to test the quality of the water. This includes the pH, TDS, EC meters and also Coliform test kits which can be used to carry out the Bacteriological tests.
Water Quality Testing
Physical Tests
- To indicate properties detectable by the senses.
Colour in water may be caused by the presence of minerals such as iron and manganese or by substances of vegetable origin such as algae and weeds.
Turbidity in water is because of suspended solids and colloidal matter. It may be due to eroded soil caused by dredging or due to the growth of micro-organisms. High turbidity makes filtration expensive. If sewage solids are present, pathogens may be encased in the particles and escape the action of chlorine during disinfection.
Total Dissolved Solids (TDS) are the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water. TDS, which is based on conductivity, is expressed in parts per million (ppm) or milligrams per liter (mg/L). TDS includes any conductive inorganic element present other than the pure water molecules (H2O) and suspended solids.
TDS affects everything that consumes, lives in or uses water, from fish and plants to plumbing and laboratories.
For people, the lower the TDS level in the water you drink, the more efficiently your body’s cells are hydrated. The higher the TDS level in water, the greater the probability of harmful contaminants that can pose health risks or hinder the absorption of water.
Odour and Taste are associated with the presence of living micro-organisms; or decaying organic matter including weeds, algae; or industrial wastes containing ammonia, phenols, halogens, hydrocarbons. While chlorination dilutes odour and taste caused by some contaminants, it generates a foul odour itself when added to waters polluted with detergents, algae and some other wastes.
Chemical Tests
- To determine the amounts of mineral and organic substances that affect water quality.
pH is a measure of hydrogen ion concentration. It is an indicator of relative acidity or alkalinity of water. Values of 9.5 and above indicate high alkalinity while values of 3 and below indicate acidity. Low pH values help in effective chlorination but cause problems with corrosion. Values below 4 generally do not support living organisms in the marine environment. Drinking water should have a pH between 6.5 and 8.5.
B.O.D.: It denotes the amount of oxygen needed by micro-organisms for decomposition of organic matter under aerobic conditions. High B.O.D. means that there is less of oxygen to support life and indicates organic pollution.
Dissolved Oxygen (DO) is important to the health of aquatic ecosystems. All aquatic animals need oxygen to survive. Natural waters with consistently high dissolved oxygen levels are most likely healthy and stable environments, and are capable of supporting a diversity of aquatic organisms. Natural and human-induced changes to the aquatic environment can affect the availability of dissolved oxygen.
Bacteriological Tests
- To show the presence of bacteria, which is a characteristic of fecal pollution in water.
The potential for waterborne diseases arises when water contains pathogenic micro-organisms which cause diseases. Common waterborne diseases are intestinal infections, dysentery, hepatitis, typhoid fever, and cholera. Testing water for pathogenic microbes is impractical as disease causing microbes are present in small numbers and they are difficult to be detected. Therefore, Coliform tests are carried out for water. Coliform bacteria are present in the intestines of animals and are released in large numbers with wastes from the body. Presence of Coliform bacteria in water indicates contamination of animal waste and presence of pathogenic micro-organisms and is not suitable for human consumption. Thus, it is important to test water for Coliform bacteria and make sure that there are none.
References
FAO, (1999). Ravikumar, R., Fishery Harbour Manual on the Prevention of Pollution, Food and Agriculture Organization.