What is Water Quality?

Water Quality refers to the physical, chemical, and biological characteristics of a water of interest. Water Quality reflects the composition of water as affected by nature and human cultural impacts and is expressed in terms of both measurable quantities and narrative qualities.

Water Quality can also be thought of as 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. The “condition” of the water is often established through comparing measurable quantities of the water’s constituents against a set of established standards or limits and thus, compliance with those standards can be assessed. The most common standards used to assess Water Quality relate to health of ecosystems, safety of human contact and drinking water. 

The most important initial principle to establish when discussing Water Quality, is the understanding that “pure” water (that is a clear, odorless, tasteless liquid consisting of only H₂O molecules) does NOT exist naturally on earth. All water found on this planet (even water subjected to the most advanced treatment technologies) will contain some amount of physical, chemical and/or biological constituents other than H₂O molecules.

It is often assumed that any substance contained in water, other than the H₂O molecules, is a pollutant (that is a contaminant that will have a negative effect on the end user), but that is not the case. As an example, water serves as a solvent and transport medium of essential electrolytes (these are minerals in your body such as sodium, potassium, calcium, and magnesium) that are essential for life. 

Where the Water Is

Water covers 71% of the earth’s surface, and the planet’s oceans contain 97% of all the water on the planet. The remaining 3% of the water on earth exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers. It is important to note that water is never sitting still. Through what we refer to as “the water cycle”, the planet’s water supply is constantly moving from one place to another and from one form to another. 

Usable water for poultry producers and processors exists either as surface water (in the form of lakes and streams) or groundwater (in the form of aquifers). Surface water is the rain runoff that flows above ground through rivers and streams until it eventually drains into the sea or ocean. The land area that collects rain runoff in a defined area is called a watershed, and no matter how far one lives from visible surface water, everyone lives in a watershed. 

Groundwater is water that percolates through the soil or enters the earth’s subsurface through sinkholes, permeable soils, and fractures in rock formations. The underground water formation is known as an aquifer within which the groundwater moves in various directions. Some aquifers are several hundred feet deep while others lie near the surface of the earth. The upper level of shallow aquifers is called the water table. It rises and falls depending on how dry or wet the season is, or how much groundwater is extracted for use. Water is constantly moving through the water cycle; thus, surface and groundwater are constantly being replenished. But water can also be used faster than it can be renewed or, in the case of groundwater, “recharged.”

Water Quality Testing

Many human activities add pollutants to surface and groundwater, principally through rain runoff. Sediments from the land, animal wastes, sewage, pesticides, detergents, oils and grease are some of the human contributions to poor Water Quality. Public domestic water supplies, which are regulated under the federal Safe Drinking Water Act, are regularly tested for contaminants. The results can be obtained from local health departments or appropriate state agencies. Most rural populations, however, obtain their drinking water from private water supplies, usually wells. These private water sources should also be analyzed frequently. 

Some of the most common analytical tests for Water Quality are (1) temperature, (2) pH, (3) alkalinity, (4) hardness, (5) specific minerals and other non-organic chemical elements (examples: Al, B, Ca, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, SiO₂, Zn), (4) total dissolved solids, (5) alkalinity, (6) anions, (7) salts, (8) nitrate, (9) lead, and (10) total coliforms/E.coli.

Physical Properties 

Physical characteristics of Water Quality include temperature, turbidity, color, odor and taste.

• Temperature: Several research studies have examined the effects of providing cool drinking water to birds during hot weather. In most of these studies, water temperature has improved the performance of broilers and layers. Any water temperature below the body temperature of the bird is beneficial. The water consumed will help dissipate body heat and aid the bird in body temperature regulation. 
• Turbidity: Turbidity is caused by the presence of very fine particles suspended in the water. These particles can be organic and/or inorganic and can include clay, silt, sand or organic material in suspension. Turbid water can cause leaky nipples and clog fogging nozzles.
• Color: Pure water is colorless and any color in water may indicate an increased contamination level. Common color associated water issues include:

1. Red, Brown or Black – Red, brown (or rust color) or black discoloration of water is often an indication of high levels of iron or manganese, 
2. Yellow – A yellow discoloration in water is often caused by source water that passes through marshlands and peat soils,
3. Blue or Green – A blue or green color is generally associated with excessive copper,
4. Cloudy/Milky White – Cloudy or milky white water can occur in the presence of dissolved air. This condition occurs when air is entrapped in water lines and dissolved in the water under pressure. When the pressure in the water line is released very fine bubbles form and give water a milky appearance. 

• Odor and Taste: issues in water can result from dissolved metals, gases, organic materials, or chemicals. Common off-tastes and nuisance odors that can cause unappealing drinking water include: 

1. Strong Chlorine taste or smell – Various forms of chlorine are used to disinfect water during the treatment process. Chlorine kills harmful bacteria and other microorganisms but can cause unappealing odors or taste if levels are too high,
2. Metallic taste – A metallic taste in water is most often associated with high levels of iron and manganese,
3. Rotten egg smell – An odor of rotten eggs in water usually indicates the decay of organic matter under anaerobic (non-oxygen) conditions. The actual rotten egg smell is hydrogen sulfide gas which is generated during the decomposition of organic matter under septic conditions. This odor in water is an indication of a serious contamination problem in the drinking water source,
4. Musty smells – Water that has a musty smell often contain organic matter or even selected pesticides. Even low levels of these substances can produce noticeable and unappealing odors.

Chemical Properties

The following parameters are of importance to the poultry industry. 

• pH: The measure of pH in water determines its acidic or alkaline (basic) quality on a logarithmic (base-10) scale of 0 – 14, with 7 being neutral. Water with a pH below 7 is considered acidic, which a pH level above 7 is basic. The logarithmic scale of pH means that water with a pH of 6 is 10-times more acidic than water with a pH of 7. Further, water with a pH of 5 is 100-times more acidic (10 x 10 = 100), than water with a pH of 7. The normal pH range of surface water systems is 6.5 – 8.5, whereas typical pH range of groundwater systems is 6.0 – 8.5. A pH of 5.0 – 6.8 is recommended for broiler production, but birds can tolerate a pH range of 4 – 8. A pH range of greater than 8 could cause reduced water consumption. 
• Alkalinity: Alkalinity is not a chemical in water, but rather, it is a property of water that is dependent on the presence of certain chemicals in the water, such as bicarbonates. It is the “buffering” capacity of water or a measure of the ability of water to neutralize acids and bases and thus maintain a stable pH. It is usually expressed in milligrams per liter of calcium carbonate (mg/L of CaCO₃). Natural waters may have less than 50 or as much as 500 mg/L of CaCO₃. These variations may be affected by the rocks and soils that the water passes through. The alkalinity varies with pH and water hardness, but sudden fluctuations may indicate a contaminant. 
• Hardness: As water moves through the earth, it becomes a solvent for minerals, such as magnesium, calcium, sulfate, and chloride. These dissolved minerals make the water “hard”. In general, the more dissolved minerals in the water, the higher its hardness level. A typical water hardness range is Soft Water = 0 – 60 mg/L, Moderately Hard Water = 61 – 120 mg/L, Hard Water = 121 – 180 mg/L, and Very Hard Water ≥ 181 mg/L. Hard water can lead to scale and sludge buildup within water lines. Hardness reduces the effectiveness of soaps, disinfectants and the administration of some medications. It is recommended that water hardness not exceed the upper level of the moderately hard water range of 120 mg/L for application in poultry producing or processing. Water softening (through ion exchange water chemistry) solves the hard water problem but may increase the amount of sodium in the water – a possible health concern for poultry and humans. 
• Minerals and other Non-Organic Total Dissolved Solids: All natural waters will contain some amount of minerals and other non-organic chemical elements in the form of total dissolved solids (TDS). TDS include calcium, magnesium, sodium, chloride, sulfate, bicarbonate, and silica. These substances, if excessive, will affect machinery and industrial processes (by clogging pipes for example, or corroding switches).
  
  TDS also affect the germination and growth of plants and the palatability of drinking water, though some minerals are desirable for their beneficial properties. Drinking water should not have more than 500 mg/L of TDS while irrigation waters may have up to 1,500 mg/L of soluble minerals. 
  
  Some specific TDS of interest to poultry producers and processors include: 
  
  • Iron (suspended and dissolved) causes problems in water if it exceeds 0.3 mg/L. Iron will stain almost everything it contacts. Recent studies indicate that Fe in the water does not appear to affect poultry health. However, some of the Fe may form solid particulates such as iron oxide, which can lead to equipment problems. These small particles can lead to leaky nipples and block fogging nozzle openings.
  • Chlorides in water should not exceed 250 mg/L; otherwise, the water may have a salty taste. Excessive chloride levels may also indicate pollution from sewage or other sources. 
  • Sulfates, which should not exceed 250 mg/L, are caused by the leaching of natural deposits of magnesium sulfate (Epsom salts) or sodium sulfate (Glauber’s salt). These salts are undesirable because of their laxative effects.
  • Nitrates (NO3-) and nitrites (NO2-) pose health problems to animals and humans, including poultry. Their presence in surface or groundwater in large amounts may indi- cate septic tank failures, over-fertilized fields, or other problems. Nitrate nitrogen levels in drinking water should not exceed10 mg/L; and nitrites, which convert to nitrates, should not exceed 1 mg/L. 
  • Phosphates: Phosphates contain phosphorus, a nonmetallic chemical element that is necessary for life and is found in rock. When water passes over or through rock, phosphorus containing molecules dissolve in the water. Phosphates also come from human sources such as sewage, agricultural runoff from crops and feedlots, the pulp and paper industry, vegetable and fruit processing, chemical manufacturing, and detergents. Large quantities of phosphates in water bodies unnaturally accelerates the process of eutrophication which leads to extreme algae and plant growth, depleting the water of oxygen. This can kill fish and degrade habitat.

• Chlorine: Chlorine is an efficient disinfectant – a chemical that kills bacteria – in water, but it can also be a contaminant if it is present in water at too high a concentration. Chlorine is added to public water supplies to kill disease-causing bacteria – pathogens – that the water or distribution pipes might contain. Chlorine should be limited in drinking water to no more than 0.05 mg/L; however, there must be a small chlorine residual in public drinking water systems to assure that the water is disinfected. 
• Dissolved oxygen (DO): DO is vital for aquatic life and can be a key test for water pollution. At DO levels below 3 mg/L, fish may become stressed or die. Generally, in unimpaired waters, dissolved oxygen ranges from 7 to 14 mg/L. However, DO levels approaching 14 mg/L on sunny days may indicate high density algae growth and possible nutrient enrichment (pollution). 
• Pesticides: Pesticides (insecticides and herbicides) enter water primarily as runoff from crop lands and thus are most prevalent in agricultural areas. They can seriously threaten groundwater, a major concern in the United States, where 50% of the population – 95% of those living in rural areas – obtains its drinking water from groundwater.

Biological Properties

Private water supplies should be tested once or twice a year for any sign of total coliform bacteria. The test for fecal coliform bacteria can differentiate between the bacteria found in soils and plants and the bacteria found in warm-blooded animals. Common symptoms of coliform bacteria in humans are intestinal bloating and diarrhea. 

Other bacteriological tests can identify many kinds and numbers of bacteria in water, but they do not separate harmful and harmless bacteria. Tests for Fecal Streptococci, Shigella, Salmonella, Staphylococci, and other bacteria may be necessary under certain circumstances. These tests are specific, time-consuming, and can be costly. They isolate bacteria that cause typhoid fever, eye and ear infections, dysentery, boils, or other skin diseases. There are also tests for viruses, protozoa, and parasites, including Giardia, Cryptospordium, Hepatitis A, and helminths. 

In surface waters, aquatic vegetation and microscopic animal and plant life may be stimulated or retarded by various water quality factors — pH, nutrients (nitrogen and phosphorus), and turbidity, among others. But growth and decay cycles may have side effects that adversely affect water quality. Even helpful substances can be come harmful in overabundance; for example, organic nitrogen in animal wastes and soils can cause “nutrient loading,” which results in low DO levels and eutrophication (i.e., an overly productive waterbody crowded with vegetation.)

Understanding Water Pollution

Potentially polluting substances in the environment can be organic or inorganic, and they are produced from both natural sources and human activities. They can be added to water through natural rain runoff, but can also enter water during industrial, agricultural, land development, or other activities that serve human needs and pleasures. In the poultry industry, for example, potential polluting substances of manure and dead birds from live production, and wastewater from poultry processing may be released to water through direct discharge, excessive runoff from the land, or leaching through the soil. 

Water in nature will always contain some components beside pure water. Water is classified as “degraded” (i.e., its quality is impaired) if it contains physical, chemical, or biological substances in sufficient quantity to restrict its use. Water Quality standards defined by the U.S. Environmental Protection Agency (EPA) identify what substances must not appear in water and at what concentrations other substances may be permissible under certain conditions. EPA has also established was tests must be performed on drinking water, surface, and groundwater to assess water quality. 

Summary

Without efficient management of poultry waste and dead birds in live production, and treatment of wastewater streams produced by poultry processing facilities, poultry operations could become a source of excess nutrients, disease-causing bacteria or viruses, and dissolved substances in our nation’s surface and groundwater supplies. Proper waste management will enhance the quality of water for everyone.

References

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Baird, R.B., A.D. Eaton, and E.W. Rice. 2017. Standard Methods for the Examination of Water and Wastewater. American Public Health Association, Washington, D.C. 

Fairchild, B.D. and C.W. Ritz. 2015. Poultry Drinking Water Primer. UGA Cooperative Extension Bulletin 1301. University of Georgia, Athens, GA. 

Federal Water Pollution Control Administration. 1968. Water Quality Criteria. Report of the National Technical Advisory Committee to the Secretary of the Interior. U.S. Government Printing Office, Washington, D.C.

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Kintzer, B.E. 1990. How poultry waste management can prevent contamination of ground and surface water. Pages 15-21 in Proceedings of the 1990 National Poultry Waste Management Symposium. National Poultry Waste Management Symposium, Auburn University Printing Service, Auburn, AL. 

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Novotny, V. 2003. Water Quality: Diffuse Pollution and Watershed Management. 2^nd ed. John Wiley & Sons, Inc. New York, NY. 

Tollner, E.W. 2002. Natural Resources Management. Iowa State Press, Ames, IA. 

Truitt, G.B. Jr. 1990. Why address the problem? An overview of the poultry system’s response to major environmental issues. Pages 7-14 in Proceedings of the 1990 National Poultry Waste Management Symposium. Auburn University Printing Service, Auburn, AL. 

U.S. Environmental Protection Agency. 2018. 2018 Edition of the Drinking Water Standards and Health Advisories. EPA 822-F-18-001. Office of Water, USEPA, Washington, DC. 

Vickers, A. 2001. Water Use and Conservation. Waterflow Press, Amherst, MA. 

Watkins, S.E. 2003. Water quality: what do we really know? Pages 32–36 in Proceedings of the 2003 Delmarva Breeder, Hatchery and Grow-out Conference. Delaware Cooperative Extension, Georgetown, DE.