Friday, April 12, 2024
Environmental Management

Concept and Principles of Water Quality

The global importance and vulnerability of our water supply, both in terms of water quantity and water quality has been well documented and, although water is a renewable resource, it is also a finite resource.

Water, vital to both human health and ecosystem sustainability, is under increasing pressure as urbanization and agricultural intensification increase and, as such, it is essential that we improve our understanding of the types, and complexity and potential impacts of chemicals that are increasingly being released into the environment, especially the water bodies, and how they affect the quality of our lives.

Definitions, Concepts, Principles and Objectives

Community Managed Water Systems: On-site or centralized drinking water systems are protected, operated and maintained (small maintenance only) by community water committee.

Contaminant: Any chemical or substance present or released or added into drinking water which is capable of being hazardous to health.

Drinking Water: All water either in its original state or after treatment, intended for drinking, cooking, food preparation or other domestic purposes, regardless of its origin and whether it is supplied from a drinking water system, or a tanker, or taken from a private well.

All water used in any food production undertaking for the manufacture, processing, preservation or marketing of products or substances intended for human consumption.

Drinking Water Quality Control: Water tests conducted on routine basis by the water utility to ensure that water supplied to the consumers meet the standard.

Drinking Water Quality Surveillance: Water tests, sanitary inspections and spot checks conducted by an independent agency to ensure that water utilities and other suppliers meet the Standard.

Drinking Water Service Level: Measure of quality, quantity, accessibility, coverage, affordability and continuity of drinking water supplied to the population. Water service levels are defined in the National Water Supply Policy and Sanitation Policy.

Drinking Water Service Provider: The whole set of organization, processes, activities, means and resources necessary for abstracting, treating, distributing or supplying drinking water and for providing the associated services. Drinking water service providers are essentially State’s water agencies. The State’s Water Agencies are:

State Water Boards/Corporations, which mostly serve urban areas greater than 20,000 inhabitants.

Small Water Town Agencies, which mostly serve semi-urban areas with population between 5,000 to 20,000 inhabitants.

Rural Water Supply and Sanitation Agencies – operate in rural areas and usually serve communities of 500 to 5,000 inhabitants.

Drinking Water System: Tangible assets necessary for abstracting, treating, distributing or supplying drinking water. Drinking water systems include centralized and on-site systems:

Protected on-site drinking water systems:

Protected hand dug wells equipped with hand pump

Protected spring catchments

Borehole equipped with hand pump

Protected centralized drinking water systems:

Mechanized borehole with distribution system

Surface water intake, treatment and distribution system

Laboratory Quality Assurance: Minimum requirements regarding staff qualification, analytical method, sampling procedures, calibration procedures, quality control, preventive maintenance and record keeping procedures that a laboratory has to comply with to ensure reliable and accurate results

Maximum Permitted or Allowable Limits: Maximum concentration of microbiological, chemical and organic constituents / contamination allowed in drinking water. These concentrations are based on WHO guideline value for which no adverse health effect is noticed.

Mineral Water: Water packaged in suitable container that meets the Nigerian Industrial Standards for Natural Mineral Water (NIS 345: 2003).

Packaged Water: Water packaged in suitable container that meets The Nigerian Industrial Standards for Potable Water.

Point of Delivery: Physical fixed interface beyond which the water service provider is not legally responsible for the service.

Point of compliance: Points where the surveillance agency collects water samples in order to measure compliance with maximum allowable limits.

Private Drinking Water System: Drinking water systems owned by a private person(s) and use solely for the family residence.

Protection Zone: Defined area surrounding a water source where activities that may affect water quality are restricted or prohibited

Public or Privately Owned Establishment: Establishment where water is supplied to the public, such as secondary schools, university, hospitals, restaurants.

Sanitary Inspections: Inspections used to evaluate the likelihood of contamination of water

Sanitary Surveys: The evaluation of the water source and intake structure, the treatment and conditioning process, the facilities and components and also an evaluation of the distribution system

Sources of Contamination: Release into the environment of man-made chemical and bacteriological contaminants. Major contamination sources are animal and human wastes, industry and mining activities, agriculture and accidents and leaks such as oil spillage.

State Urban Water Supply Regulators: Independent regulatory bodies that monitor the performance of water utilities or any other water supply operators and ensure that the water supply complies with quality standard and service levels.

Toxicelement: Organic or inorganic constituents that may adversely affect human health when its concentration in water reaches a specific threshold.

Water quality: The chemical, physical, biological, and radiological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose.

Water Source (ground water or surface water)

Surface water includes streams, rivers, lakes or reservoirs.

Ground water includes springs, wells or boreholes

Water Safety Plan: Essential actions that are the responsibility of the drinking water provider in order to ensure that drinking water is safe. These are: A system assessment; Effective operational monitoring; and Management.

Water Vendors: These are persons or organizations selling water to households or at collection points. Vendors may carry drinking water for sale directly to the consumer by tanker trucks, wheelbarrows /trolleys or donkey carts

Concept of Water Quality

Pollution influences living organisms, humans included, both directly (by affecting their health) and indirectly (via contamination of food and abiotic compartments).

Heavy metals and organic compounds, such as polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), volatile organic compounds (VOCs) and pesticides, have been the center of attention for a long time.

It is necessary to understand the nature of these pollutants and their effects on water quality for the development of better management practices.

The importance of water quality as a factor constraining water use has often gone unacknowledged in the analyses of water scarcity. Water scarcity is a function not only of volumetric supply, but also of quality sufficient to meet the demand.

The UN World Water Development Report from the World Water Assessment Program indicates that, in the next 20 years, the quantity of water available to everyone is predicted to decrease by 30%.

More than 2.2 million people died in 2000 from waterborne diseases (related to the consumption of contaminated water) or drought. In 2004, the UK charity WaterAid reported that a child dies every 15 seconds from easily preventable water-related diseases.

Some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability (Kulshreshtha, 1998). A report, issued in November 2009, suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.

Water plays an important role in the world economy. Water quality management is important because safe drinking water is essential to humans and other life forms. The drinking water demand is perhaps the largest demand for high quality water apart from many industrial uses which also require high quality water.

Water is an excellent solvent for a wide variety of chemical substances; as such it is widely used in industrial processes, and in cooking and washing. Agriculture, by far the largest consumer of water, also suffers when water supplies is affected.

Other anthropogenic activities that use water include fishing, transport, cooling and heating in industries and homes etc.

Water Quality Principles

The following guiding principles provide a suitable basis for water quality management:

Prevent pollution rather than treating symptoms of pollution. Remedial actions to clean up polluted sites and water bodies are generally much more expensive than applying measures to prevent pollution from occurring. This principle seeks to prevent the production of wastes that require treatment.

Water pollution control that focuses on wastewater minimization, in-plant refinement of raw materials and production processes, recycling of waste products, etc., are given priority over traditional end-of-pipe treatments.

Where water pollution originates from diffuse sources, such as agricultural use of fertilizers, which cannot be controlled by this approach the principle of “best environmental practice” should be applied to minimize non-point source pollution e.g. codes of good agricultural practice that address the causes of water pollution from agriculture, such as type, amount and time of application of fertilizers, manure and pesticides, can give guidance to farmers on how to prevent or reduce pollution of water bodies. (UNECE, 1993).

Precautionary Principle

There are many examples of the application and discharge of hazardous substances into the aquatic environment, even when such substances are suspected of having detrimental effects on the environment.

Until now the use of any substance and its release to the environment has been widely accepted, unless scientific research has proved unambiguously a causal link between the substance and a well-defined environmental impact.

Actions to avoid potential environmental damage by hazardous substances should not be postponed on the grounds that scientific research has not proved fully a causal link between the substance and the potential damage (UNECE, 1994).


The costs of pollution prevention, control and reduction measures are borne by the polluter. This principle is an economic instrument that is aimed at affecting behaviour, i.e. by encouraging and inducing behaviour that puts less strain on the environment.

Examples of attempts to apply this principle include financial charges for industrial waste- water discharges and special taxes on pesticides (Warford, 1994).

Read Also : Protection and Development of Water Resources Guide

Realistic Standards and Regulations

An important element in a water pollution control strategy is the formulation of realistic standards and regulations. However, the standards must be achievable and the regulations enforceable.

Unrealistic standards and non-enforceable regulations may do more harm than having no standards and regulations, because they create an attitude of indifference towards rules and regulations in general, both among polluters and administrators.

Standards and regulations should be tailored to match the level of economic and administrative capacity and capability.

Standards should be gradually tightened as progress is achieved in general development and in the economic capability of the private sector. Thus, the setting of standards and regulations should be an iterative and on-going process.

Balance Economic and Regulatory Instruments

Regulatory management instruments are heavily relied upon by governments in most countries for controlling water pollution.

Economic instruments, typically in the form of wastewater discharge fees and fines, have been introduced to a lesser extent and mainly by industrialized countries. The setting of prices and charges are crucial to the success of economic instruments.

If charges are too low, polluters may opt to pollute and to pay, whereas if charges are too high, they may inhibit economic development. In developing countries, where financial resources and institutional capacity are very limited, the most important criteria for balancing economic and regulatory instruments should be cost-effectiveness (those that achieve the objectives at the least cost) and administrative feasibility.

Water Pollution Control at the Lowest Appropriate Level

The appropriate level may be defined as the level at which significant impacts are experienced. If, for example, a specific water quality issue only has a possible impact within a local community, then the community level is the proper management level.

If environmental impacts affect a neighboring community, then the appropriate management level is one level higher than the community level, for example the river basin level.

The important point is that decisions or actions concerning water pollution control should be taken as close as possible to those affected, and that higher administrative levels should enable lower levels to carry out decentralized management.

Establishment of Mechanisms for Cross-Sectorial Integration

In order to ensure the co-ordination of water pollution control efforts within water-related sectors, such as health and agriculture, formal mechanisms and means of co-operation and information exchange need to be established. Such mechanisms should:

Allow decision makers from different sectors to influence water pollution policy.

Urge them to put forward ideas and plans from their own sector with impacts on water quality.

Allow them to comment on ideas and plans put forward by other sectors.

For example, a permanent committee with representatives from the involved sectors could be established. The functions and responsibilities of the cross-sectoral body would typically include at least the following:

Co-ordination of policy formulation on water pollution control.

Setting of national water quality criteria and standards, and their supporting regulations.

Review and co-ordination of development plans that affect water quality.

Resolution of conflicts between governments bodies regarding water pollution issues that cannot be resolved at a lower level.

Participatory Approach with Involvement of All Relevant Stakeholders

The participatory approach involves raising awareness of the importance of water pollution control among policy-makers and the general public.

Decisions should be taken with full public consultation and with the involvement of groups affected by the planning and implementation of water pollution control activities.

Water Quality

This means, for example, that the public should be kept continuously informed, be given opportunities to express their views, knowledge and priorities, and it should be apparent that their views have been taken into account.

Open Access to Information on Water Pollution

This principle is directly related to the principle of involvement of the general public in the decision-making process, because a precondition for participation is free access to information held by public authorities. Open access to information helps to stimulate understanding, discussions and suggestions for solutions of water quality problems.

International Co-Operation on Water Pollution Control

Trans-boundary water pollution, typically encountered in large rivers, requires international co-operation and co-ordination of efforts in order to be effective.

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In a number of cases (e.g. the Danube, Zambezi and Mekong rivers), permanent international bodies with representatives from riparian states have been successfully established, with the objective of strengthening international co-operation on the pollution control of the shared water resources.

A framework for international co- operation on water pollution control that has been widely agreed is the Convention on the Protection and Use of Trans-boundary Watercourses and International Lakes (UNECE, 1994).

Water Quality Criteria and Objectives

Water quality criterion (or water quality guideline) refers to numerical concentration or narrative statement recommended to support and maintain a designated water use.

Water quality objective (water quality goal or target) on the other hand refers to numerical concentration or narrative statement which has been established to support and to protect the designated uses of water at a specific site, river basin or part(s) thereof.

Water Quality Criteria

Water quality criteria are developed to provide basic scientific information about the effects of water pollutants on a specific water use. They also describe water quality requirements for protecting and maintaining an individual use.

Many water quality criteria set a maximum level for the concentration of a substance in a particular medium (i.e. water, sediment or biota) which will not be harmful when the specific medium is used continuously for a single, specific purpose.

For some other water quality variables, such as dissolved oxygen, water quality criteria are set at the minimum acceptable concentration to ensure the maintenance of biological functions.

Water Quality Criteria for Individual Use Categories

Water quality criteria have been widely established for a number of traditional water quality variables such as pH, dissolved oxygen, biochemical oxygen demand for periods of five or seven days (BOD5 and BOD 7), chemical oxygen demand (COD) and nutrients.

In setting criteria for water quality water-management authorities in consultation with industries, municipalities, farmers’ associations, the general public and others agree on the designated water uses in a catchment area that are to be protected.

Such uses include categories such as drinking-water supply, irrigation, livestock watering, fisheries, leisure activities, amenities, maintenance of aquatic life and the protection of the integrity of aquatic ecosystems etc.

Each of these uses have different requirements that will therefore inform the water quality goal or target (objectives).

Water Quality Objectives

The establishment of water quality objectives is not a scientific task but rather a political process that requires a critical assessment of national priorities.

Such an assessment is based on economic considerations, present and future water uses, forecasts for industrial progress and for the development of agriculture, and many other socio-economic factors (UNESCO/WHO, 1978; UNECE, 1993, 1995).

General guidance for developing water quality objectives is given in the Convention on the Protection and Use of Trans-boundary Watercourses and International Lakes (UNECE, 1992).

Water quality objectives provide the basis for pollution control regulations and for carrying out specific measures for the prevention, control or reduction of water pollution and other adverse impacts on aquatic ecosystems.

In some countries, water quality objectives play the role of a regulatory instrument or even become legally binding. Their application may require, for example, the appropriate strengthening of emission standards and other measures for tightening control over point and diffuse pollution sources.

In some cases, water quality objectives serve as planning instruments and/or as the basis for the establishment of priorities in reducing pollution levels by substances and/or by sources.

The establishment of a time schedule for attaining water quality objectives is mainly influenced by the existing water quality, the urgency of control measures and the prevailing economic and social conditions.

It is of the utmost importance that the objectives are understandable to all parties involved in pollution control and are convertible into operational and cost-effective measures which can be addressed through targets to reduce pollution.

It should also be possible to monitor, with existing networks and equipment, compliance with such objectives. Objectives that are either vague or too sophisticated should be avoided. The objectives should also have realistic time schedules.

In summary, water quality objectives should be revised regularly in order to adjust them, among other things, to the potential of pollution reduction offered by new technologies, to new scientific knowledge on water quality criteria, and to changes in water use.

So far, we have looked at the definitions and some basic concepts associated with water quality management. The underlining principles of water quality were studied as follows:

  • Prevent pollutants rather than treating the symptoms of pollution.
  • Precautionary principle.
  • Polluter-pays principle.
  • Realistic standards and regulations.
  • Balance economic and regulatory instruments.
  • Water pollution control at the lowest appropriate levels.
  • Establishment of mechanism for cross-sectorial integration.
  • Participatory approach with involvement of all relevant stakeholders.
  • Open access to information on water pollution.
  • International co-operation on water pollution control.

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Benadine Nonye is an agricultural consultant and a writer with over 12 years of professional experience in the agriculture industry. - National Diploma in Agricultural Technology - Bachelor's Degree in Agricultural Science - Master's Degree in Science Education... Visit My Websites On: 1. - Your Comprehensive Practical Agricultural Knowledge and Farmer’s Guide Website! 2. - For Effective Environmental Management through Proper Waste Management and Recycling Practices! Join Me On: Twitter: @benadinenonye - Instagram: benadinenonye - LinkedIn: benadinenonye - YouTube: Agric4Profits TV and WealthInWastes TV - Pinterest: BenadineNonye4u - Facebook: BenadineNonye

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