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Water Quality and Standards


  1. History of Water Quality Standards
  2. Importance of Water Quality Standards
  3. National and International Water Quality Standards
  4. Chemical and Bacteriological Characteristics

   Water is very important for our life. Therefore, water must be free from organisms that are capable of causing disease and  from  minerals  and  organic  substances   that  could produce adverse physiological effects (Pontius, 1990).

Drinking water should be aesthetically acceptable; it should be free from apparent  turbidity,  color,  and  odor  and  from  any  objectionable  taste. Water meeting these conditions is termed ”Potable  Water”. This means that  it  may  be  consumed  in  any  desired  amount  without  concern  for adverse effects on health ( Pontius, 1990).

History of Water Quality Standards

Water quality was hot very well documented and people knew relatively little about disease as it related to water quality. Early historical treatment was performed only for the improvement of the appearance or taste of the water.  No  definite  standards  of  quality  other  than  general  clarity  or palatability  were  recorded  by  ancient  civilizations.  The  first  drinking water standards were issued at least 4000 years ago.
Hippocrates, the father of medicine, stated that ”water contributes much to health.” His interest in water centered on the purifying the most health- giving source of supply rather than on purifying the waters that were bad. Apparently, ancient  people deduced by observation that certain waters promoted good health. While others produced infection.
By the 18th  century, filtration of particles from water was established as an effective means of  clarifying water. The general practice of making  water clean was well recognized by that time, but the degree of clarity was  not  measurable.

The  first  municipal  water  filtration  plant  started operations in 1832 in Scotland. Aside from the  frequent references  of concern for the aesthetic properties of water, historical records indicate that standards for water quality were notable absent up to and including much of the 19th century.
With the realization that various epidemics (e.g., cholera and typhoid) had been caused  and  spread  by water  contamination,  people  saw  that  the quality  of  drinking  water  could  not  be  accurately  judged  by  sensory perception. Reliance on taste and smell was not an accurate means of judging  the acceptability of water; more stringent quality criteria would be a necessary historical  development.  As a result, in 1852 a law was passed in London stating that all waters should be filtered.

In the mid-1890s, the Louisville Water Company, Louisville, combined coagulation with rapid sand filtration, significantly reducing turbidity and bacteria in the water.

The next major milestone in drinking water technology was the use of chlorine  as  disinfection.  Chlorination  was  first  used  in 1908  and  was introduced in a large number of water systems.

In  the  19th   century,  the  water  quality  standards  was  developed  and regulated  to  give  best  potable  water.  These  standards  (Pontius,  1990) included the following :

  1.  The  basic  formal  and  comprehensive  review  of  drinking  water concerns was launched.
  2.   The concept of maximum permissible and safe limit was introduced.
  3.   Physical and Chemical constituents were limited.
  4.  Physical, Chemical, and bacteriological examinations were illustrated.
  5.  Samples for bacteriological examination were to be obtained from pointes in the distribution system.
  6.  Maximum concentrations, not to be exceeded always, where more suitable.

Importance of Water Quality Standards

Water quality standards normally identify the concentration of component properties shown by examinations of water samples to be safe, acceptable and attainable from available sources.
The maximum permitted  concentration of various  substances  in public water supply is controlled  throughout the world by legislation and varies to some extent from country to country.

Standards of water quality (Babbitt et al, 1962) can be divided into three types:

  1.   For water of exceptionally great natural purity.
  2.   For pure waters from a restricted area, and.
  3.   For limits of matters permitted in water.
  • National and International Water Quality Standards

Several water quality standards were established and implemented. Some of these are still in use,  whereas, some were modified. National (Saudi Arabian Standards) and selected international water quality standards for drinking water which are currently in use are presented in Table 3.1. Brief
information about these standards is presented below.

  • Saudi Arabian Standards SASO

Drinking water quality  standards in Saudi Arabia (SAS) are issued by the Saudi Arabian Standards  Organization (SASO). There are two drinking water quality standards currently in use in Saudi  Arabia. These are the bottled drinking water quality standards (SASO, 1997) and the unbolted drinking  water  quality  standards  (GCS.  1993).  The  former  have  been issued in 1392 H (1972 G) by the Saudi Arabian Standards Organization (SASO) and implemented in 1405 H (1985 G). The un  bottled drinking water quality standards have been issued in 1403 H (1982 G) by the Saudi Arabian Standards Organization (SASO  and standardization and Metrology Organization for Gulf Council Countries (GSMO)  and  implemented  in 1413 H (1993  G). The  bottled  drinking water quality standards are currently in use of the  water  quality in the distribution system.

  • Gulf Cooperation Countries Standards

Gulf Cooperation Council Countries Standards are the ”Unbottled Drinking Water Quality Standards” (GCS, 1993) which have been issued in 1403 H (1982 G) by the Saudi Arabia Standards Organization (SASO) and  Standardization and  Metrology  Organization for  Gulf  Cooperation Council Countries (GSMO).

  • World  Health  Organization  Guide  for  Drinking  Water Quality

The primary aim of the World Health Organization (WHO) Guidelines for drinking water quality is  the protection of public health and thus the elimination,  or  reduction  to  a  minimum,  of  constituents  in  water  that known to be hazardous to the health and well-being of the community
(Pontius, 1990).

  • USA Environmental Protection Agency for Drinking Water Regulations

United StatesEnvironmental Protection Agency (USEPA’s) secondary regulations set desirable levels for  drinking water contaminants that may adversely affect the aesthetic value of drinking water. States may establish higher or lower levels  that may be appropriate  depending upon local conditions such  as  unavailability  of  alternative  source  water  or  other  compelling factors,  provided  that  public   health  and  welfare  are  not adversely affected.
The present standards include maximum contaminant le4vel (MCL), also known as primary  standards,  for those organic and inorganic chemicals known  to  have  toxic  or  carcinogenic  effects,   for  turbidity,  and  for bacterial  population. In addition, recommended contaminant  levels. (RCL, secondary standards) have been established for certain contaminants, which are primarily of esthetic importance (Pontius, 1990).

  • European Economic Community Drinking Water Directives

The European Economic Community (EEC), having been established by a treaty of the Council of  the  European Communities, issued a council directive relating to the quality of water intended for human consumption. Specifically, the EEC standards provide for both the setting of standards to apply to toxic chemicals and bacteria that present a health hazard, and the definition of   physical, chemical, and biological parameters for different uses of water. Specifically for the use of human consumption
(Pontius, 1990).

  • Canadian Drinking Water Guidelines

In Canadian, drinking water is a shared federal-provincial responsibility. In general, provincial  governments are responsible for an adequate, safe supply, whereas the Federal Department of National Health and Welfare develops quality guidelines and conducts research. Guidelines for Canadian Drinking water quality (CGL) are developed through a joint federal-provincial  mechanism  and  are  not  legally  enforceable  unlesss promulgated as regulations by the appropriate provincial agency. The first comprehensive Canadian drinking water guidelines were published by the Department of National Health and Welfare in 1968. They were
completely revised in 1978 and again in 1987. (Pontius, 1990).

Water Quality standard

water quality standard


 Chemical Characteristics

  • pH

pH is a measured of the acidic or basic (alkaline) nature of a solution. The concentration of the hydrogen ion (H+) morality in a solution determines the pH.
Pure water has pH equal 7 and is neutral. Water with a pH less than 7 is acidic, and water with pH  greater than 7 is basic. The principle system regulating  pH  in  natural  water  is  the  carbonate  system  composed  of carbon dioxide, carbonic acid, bicarbonate ions, and carbonate ions. PH is an  important  factor  in  the  chemical  and  biological  system  of  natural water. The degree of dissociation of weak acids or bases is affected by changes in pH.

  • Electrical Conductivity

Electrical conductivity is a numerical expression that shown the ability of water  to  hold  electrical  current.  The  unit  of Electrical  conductivity  is mhos / cm.  Electrical conductivity depends on the  ionic forces  of the solution, appearance of the dissolved ions and their concentration, relative concentration, and the measurement temperature.

  • Total dissolved Solid

Total dissolved Solid is the summation of all dissolves solids in the water, such as  non-organic  materials,  carbonate,  bicarbonate,  nitrate,  sodium, potassium, chloride, and magnesium. TDS affects the other characteristics
of drinking water such as taste and hardness.

  • Dissolved Oxygen

Dissolved  Oxygen analysis  measure  the  amount  of  gaseous  oxygen dissolved an aqueous solution. Oxygen gets into water by diffusion from the surrounding air, by aeration, and as a waste product of photosynthesis. It  generally  ahs  also  been  considered  significant  in  the  protection  of aesthetic qualities.
Dissolved Oxygen concentration are an important tool to determine the ability  of  a  water  body   to   support  a  well-balanced  aquatic  fauna. Insufficient.
Dissolved Oxygen in the water column causes the anaerobic decomposition of organic materials leading to the formation of noxious gases,  such  has  hydrogen  sulfide,  and  the  development  of  carbon dioxide an methane in sediments that bubble to the surface or which tend to float sludge.
Dissolved Oxygen in municipal water supplies is desired as an indicator of  satisfactory  water  quality  in  terms  of  low  residual  of  biologically available  organic  material.  In  addition,  oxygen  in  water  prevents  the chemical  reduction  and  subsequent  leaching  of  iron  and  manganese, principally  from  the  sediments.  On  the  other  hand,  excess  oxygen increases the rate of metal corrosion, which can increase the concentration of iron and other metals in drinking water supplies.

  • Alkalinity

The alkalinity of the water is its ability to neutralize an acid. It is the sum total of components in the water that tend to elevate the pH of the water
above 4.5. Carbonates, bicarbonates, phosphates, and hydroxide

 contribute the common materials in natural water that increase alkalinity. Alkalinity resulting from naturally occurring materials is not considered a health  hazard  in  drinking  water  supplies.  Maximum  levels  up  to  400 mg/L as calcium carbonates are not considered a problem.

  • Nitrates

The continuous  interchange between atmospheric terrestrial nitrogen is referred to as nitrogen cycle. It has undergone profound modifications as a result of agricultural and industrial activities of man.
Atmospheric nitrogen is transformed by microbial action in plants and in the  soil,  by  various  atmospheric  processes,  and  by  industrial  process compounds, such as ammonia, nitrates, and nitrites.
Nitrates are salts of nitric acid, most of which are readily soluble in water. Levels  in  cultivated  soils,   and  thus  levels  in  groundwater,  may  be increased  by  the  use  of  commercial  nitrogenous  fertilizers  and  farm animal  waste.  Intensive  animal  farming  produces  large  amounts of nitrogenous materials that may be converted into nitrates.

  •  Chloride

Chloride ion is one of  the major inorganic anions in water and wastewater. Chloride is a salt compound resulting from the combination of the gas, chlorine, and metal. The typical taste may be absent in waters containing as much as 1,000 mg/L when the  predominant cautions are calcium and magnesium.
The  chloride  concentration is  higher  in wastewater  than in raw  water because sodium chloride is  a  common component of the diet and passes
unchanged  through  the  digestive  system.  High  chloride  content  may

 metallic pipes and structures,  as  well as  growing plants. Chloride can corrode metals and affect the taste of food products. Therefore, water is used in industry or processed for any use has a  recommended maximum chloride level.

  •  Calcium

The pressure of calcium in the form Ca2+ in water supplies as a result of passage through or over  deposits of limestone, dolomite, gypsum, and gypsiferous shale. The calcium content may range  from  zero to several hundred milligrams per liter, depending on the source and treatment of the water. Calcium contributes to the total hardness of water.

  •  Magnesium

Magnesium, in the form of Mg2+, ranks eighth among the elements in order  of  abundance  and  is   a  common  constituent  of  natural  water. Important contributes to the hardness of water,  magnesium  salts breaks down when heated, forming scale in boilers. The magnesium may very from  zero  to  several  hundred  milligrams  per  liter,  depending  on  the source and treatment of the water.

  • Sodium

Sodium, in the form of Na+, ranks sixth among the elements in order of abundance and is present  in  most natural waters. The levels may very from less than 1 mg Na/1, to more than 500 mg Na/1. The ratio of sodium to total cations is important in agricultural and human pathology.

  •  Potassium

Potassium, in the form of K, ranks seventh among the elements in order of  abundance,  yet  its  concentration  in  most  drinking  waters  seldom   reaches 20 mg/L. However, occasional brines may contain more than 100 mg/L potassium.

  • Phosphorus

Phosphorus, in the  form of P+,  is  particularly toxic  and is  subject  to bioaccumulation in much same way as mercury. However, phosphorus as phosphate  (PO4+)  is  one  of  the  major  mutrients required  for  plant nutrition and essential for life. Phosphorus enters waterways from several different sources.
The human body excretes about 1 pound per year of phosphorus. The use of  phosphate  detergents  and  other  domestic  phosphates  increases  the phosphorus  load  to  natural  habitats.  Some  industries,  such  as  potato processing, have wastewater high in phosphates. It was found that total phosphorus concentrations  in excess of 100 mg/L might interfere with coagulation in water treatment plants.

  •  Ammonia

Ammonia in the form of NH3 is a pungent, colorless, gaseous, alkaline compound of nitrogen and hydrogen that is highly soluble in water. It is a biologically  active  compound  present  in  natural  waters  as  a  normal biological degradation product of nitrogenous organic matter and wastewater. It may also reach surface waters through the  discharge of industrial  wastes  containing  ammonia  as  a  byproduct  or  wastes  from
industrial processes using ”ammonia water”.

  •  Cadmium

Cadmium in the  form of (Cd)  occurs  as  a  soft,  blue-white,  malleable metal or grayish-white powder. Cadmium has been shown to be toxic to man  when  ingested  or  inhaled.  When  ingested,   it  caused  symptoms resembling food poisoning.
The naturally occurring presence of cadmium in the environment results mainly from gradual phenomena, such as rock erosion and abrasion, and of singular occurrences, such as volcanic eruptions. Cadmium is, therefore, naturally present in air, water, soil, and foodstuffs. It is soluble in acid, ammonium nitrate, and insoluble in water.

  • Lead

Lead in the form of (Pb) is a silver-gray soft metal that occurs in the earth’s at crust at an average  concentration of about 13 mg/kg, however, some  environment have much higher  concentrations.  Since these areas constitute a small percentage of total land, exposures of man to  these sources are negligible.
People  are  exposed  to  lead  by  ingestion  of  food  and  fluids  and  by inhalation. Man’s intake of lead through water, particularly in urban areas, is generally low in comparison with exposure through air and food.

  • Chemical Oxygen Demand (COD)

Chemical oxygen demand is a measure of water pollution resulting from organic matter. STET the  amount of oxygen required, or equivalent, for the oxidation of all chemically oxidyzable matter  contained in a water
sample.  This  is  accomplished  using  a  number  of  methods  utilizing  a     strong  chemical  oxidant.  Boiling  a  solution  containing  chromic  and sulfuric acids can digest the majority or organic matter.

 Bacteriological Characteristics

  •  Fecal coliform Bacteria

Total coliforms are measure of thee concentration of bacteria associated with the presence of  sewage  pollution. Fecal coliform bacteria are the most  frequently  applied  microbiological  indicators  of  water  quality  to determine  the  safety  of  water  for  drinking,  swimming,  and  shellfish harvesting.
The coliform group is made up of a number of bacteria. Total coliform bacteria are all gram-negative asporogenous rods and have been associated  with faces of warm-blooded animals and with soil. They are able to grow at 44.50C and ferment lactose, producing acid and gas. Use of fecal coliform bacteria has proven to be of more sanitary significance than the use of total coliform bacteria because to define water quality for swimming.
The presence of fecal coliform bacteria in aquatie environments indicates that the water has been  contaminated with the fecal material of man or other animals. At the time this occurred, the source  water might have been contaminated by pathogens or disease producing bacteria or viruses, which  can  also  exist  in  fecal  material.  Some  waterborne  pathogenic diseases  include  typhoid  fever,  viral  and  bacterial  gastroenteritis,  and hepatitis A.

 The presence of fecal contamination is an indicator that a potential health risk exists for individual  exposed to this water, fecal coliform bacterial may  occur  in  ambient  water  as  a  result  of  the  overflow  of  domestic sewage  or  nonpoint  sources  of  human  and  animal  waste.  Shellfish concentrates  fecal  coliform  bacteria, other  bacterial  pathogens, and viruses found in water and sediment. Shellfish, as filter feeders, require a high quality of water in  order  to be microbiologically safe for  human consumption, either raw or partially cooked.

One Response to “Water Quality and Standards”

  1. Ajithkumar says:

    wish you all the best,



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