Review of the Effects of Water Characteristics and Quality on Human Health

This paper reviews water quality parameters and their health effects on humans with the objective of enlightening the public on drinking water guidelines, the focal point and protection measures. It is also intended to help evade the health catastrophe that manifests as a result of ingesting water containing substances in excess concentration of recommended limits. Sources of water are reviewed, including rain water, surface water and groundwater. The presence and level of the biological, physical and chemical constituents referred to as water parameters which determine its suitability for drinking were also reviewed. Biological parameters are microorganisms, while physico-chemical parameters include temperature, color, dissolved solids, cations, etc. Drinking water quality standards as well as the health impacts of water quality parameters were discussed. Some of the health impacts include water borne diseases, organ failures, cancer, neurological damage, etc. The paper concludes that microorganisms and chemical constituents in drinking water sources and supply can directly or indirectly impair the use of the water for human consumption. Recommendations were made including the disinfection of drinking water sources to prevent growth of disease causing organisms, hand washing to prevent infections including Covid 19 virus and laboratory assessment of water quality parameters to ascertain their conformity with drinking water standards.


INTRODUCTION
Drinking water is one of the most essential, inevitable and indispensable natural resources needed for life existence and man's survival (Subramani et al., 2005, Nwankwoala et al., 2012. It is needed for daily use by all living organisms including plants, animals and human beings. Due to its unique properties, water serves multiple uses. Water is used for drinking, irrigation, transportation, recreation, washing, cooking, industrial activities and many more. Therefore, it is absolutely essential for life. Human beings depend on water at all developmental stages and activities (Srivastava, 2015). All water including drinking water, contain naturally occurring substances which are categorized into physical, chemical and biological constituents (characteristics). The level and type of the substances in the water determine its suitability for any purpose. The level and presence of physicochemical and biological parameters (substances) are expected to be within the recommended (maximum permissible) limits set by regulatory bodies to protect human health. Within this recommended range, substances (parameters) will not pose any health threat to water consumers, but deviation from the limit in excess of the recommended level, will result in human health catastrophe. The biological properties of water indicate the presence of micro-organisms such as viruses, bacteria, fungi, protozoa etc. These organisms are naturally present in water and consequently lead to water related diseases, especially when in contact with contaminated and untreated sources. Any water source serving consumption purpose should be devoid of these microorganisms or be disinfected in order to avert health dangers associated with drinking microbial-contaminated water. Health risks and challenges involved by ingesting a biologically polluted water are enormous, leading to outbreak of diseases within a particular community or even death. The physicochemical properties are made up of parameters such as, temperature, colour, odour, suspended solids, dissolved solids, bicarbonates, chlorides, sodium, nitrates, sulphates, calcium, magnesium, potassium, etc. These substances are naturally found in drinking water sources in amount that may or may not be detrimental to human health especially when consumed without proper treatment. Water is pure in its own nature, but the pathway on earth imparts additional impurities and contaminants found in it. Human and man-made activities also contribute contaminants prevalent in water (Peavy et al., 1985;Venkateswaran & Deepa, 2015). The presence of contaminated substances and impurities in water can impair its intended use. Therefore, it is imperative to study water with intent to ascertain its quality and impacts on human health and environment. These impurities found in water may be inform of suspended or dissolved solids. Dissolved materials consist of molecules or ions that are held by the molecular structure of the water which can only be assessed through laboratory analysis. Therefore water quality of drinking sources is a worldwide concern and very important for public health (Levallios & Villanueva, 2019). Understanding water characteristics with reference to its quality and health implications, will definitely help to curb both short and long term diseases incurred as a result of drinking contaminated water. The aim of this paper is to review water characteristics and its quality with the objectives of outlining the implications associated with water quality parameters in excess of the recommended range on human health. It will also raise awareness and enlighten the public. Narsimha et al., 2013 stated that the backbone for prevention, protection and control of water -borne and related diseases lies in proper management of drinking water which directly empowers sustainable economy and development.

SOURCES OF WATER
Water occur and circulate on the earth surface through hydrological cycle and a process called precipitation. Precipitation is the release of saturated water vapor from the atmosphere to the earth surface in forms of rain, hail, sleet, drizzle, etc. (Reddy, 2008). The various places on the earth surface from which this water can be collected or extracted for human use depicts its source. Sources of water include rain water, surface water and ground water.

Rain Water
Rain water is a natural and major source of water supply in most rural areas. And for such areas, it might be the only source of water for drinking and other purposes. Therefore, it can be properly harvested, collected and stored for desired purposes. It is usually collected from building roofs and land surfaces (Agunwamba, 2000). Rainwater that is collected and stored correctly is safe, economical and also sustainable (Srivastava, 2015). Rain water is soft and most suitable for laundry purposes. It offers a better washing efficiency. It is free and requires no elaborate purification works. No transmission and distribution network is required. It causes no calcification in washing machines. Although it may be corrosive due to its travel surface.

Surface Water
Surface water is accumulated water body in a particular area with an open surface. It includes rivers, lakes, ponds, streams, oceans, etc. This particular water is an open source on land surface and very susceptible to contamination and quality deterioration by human and animal activities. They are mostly harnessed for water supply in urban areas by state water co-operations due to its sustaining perennial condition. Also due to lack of proximity, it requires more piping network, treatment system, storage facilities and professional skills, to design and construct water supply system to communities. These factors directly spike the cost of construction of water supply system and such projects can only be financed or sponsored by federal or state government. Surface water is the major sources of water supply, in some areas (Kumar et al., 2009;Avvannavar & Shrihari, 2008) Ground Water Groundwater is formed by rainfall which infiltrates into the ground through the pores of rock and soil to underground water table (Arora, 2007). Groundwater exists in pore spaces of soil and rock sediments and are fully saturated (Todd and Mays, 2000;Mahalingam et al., 2014). It varies in quality depending on the geological conditions of the soil through which it passes through or flows (Ocheri et al., 2014). It includes wells, boreholes, etc. It can be abstracted from the aquifer by means of hand dug well and boreholes at various depths (Ezomo et al., 2013). Hand dug wells are manually sited by individuals to meet their domestic water demands. Siting of boreholes within a community or home requires proper geological and geophysical investigation of viable aquifer before drilling to guide against influences of seasonal variations on water level and yield. Conversely, improper siting of boreholes may lead to its failure or insufficient water abstraction during the dry season. Singh et al. (2011) reported that groundwater are mainly utilized in areas with shortages or no supply of water from water board. cause 485,000 diarrhoeal deaths each year (WHO/UNICEF, 2020). Outbreaks of water borne diseases in a community must be seriously avoided and curbed due to its consequential health implication and impact on the masses (WHO, 2011). Diseases such as, trachoma, leprosy, tuberculosis, whooping cough, tetanus and diphtheria, skin infections are regarded as water scarce diseases. They are predominantly found in areas with water scarcity and very poor hygiene and environmental sanitation. Their transmission will be reduced by increasing the volume of water used for hygienic purposes (Agunwamba, 2000). Aquatic organisms that spend part of their life cycle in the water and another part as parasites of animals cause water based diseases. These organisms can thrive in either polluted or unpolluted water. They include guinea worm (dracunculiasis), paragomimiais, and schistosomiasis (bilharzia). These diseases are caused by a variety of flukes, tapeworms, roundworms and tissue nematodes, often collectively referred to as helminthes that infect humans. Although they are usually not fatal but they can be extremely painful, prevent people from working and sometimes make movement impossible. Millions of people suffer from infections that are transmitted by vectors-insects or other animals capable of transmitting an infection such as mosquitoes and tsetse-flies, that breed and live in or near both polluted and unpolluted water (Agunwamba, 2000). Such vectors infect humans with malaria, yellow fever, sleeping sickness and filariasis. Microbial or bacteriological analysis of water involves the estimation and isolation of microorganisms present in the water sample. Each of these organisms are individually screened and detected through specific techniques which is time consuming and expensive (Peavy et al., 1985). In addition, they cannot easily be handled in laboratory and are relatively difficult to isolate and identify, hence the use of indicator organisms. Indicator organisms comprise faecal and total coliform generally referred to as coliform organisms. They are more numerous, less harmful and easily tested for. Their presence indicates and signifies that contamination has occurred which originates from human and animal intestines as well as the presence of pathogenic organisms (Weiner & Matthews, 2003). Drinking water source is tested for these coliform bacteria to ensure absence or presence of water borne pathogens and the suitable treatment where necessary (Parker et al., 2010) Physical Water Characteristics Physical water characteristics are regarded as those characteristics that can be identified through human senses i.e., sight, smell, touch and taste. They include temperature, turbidity, suspended solids, colour, taste and odour. a. Temperature: Temperature of water determines its suitability for human use, industrial application and aquatic ecosystem functioning (Subramani et al., 2012). To a large extent, it governs the biological species present and their rates of activities (Al-Layla et al., 1978). It has effect on most chemical reactions that occur in natural water systems and solubility of gases in water (Peavy et al., 1985).

b. Turbidity
Turbidity is a measure of the extent to which light is either absorbed or scattered by suspended material in water. It is cloudy and prevents visibility (Agunwamba, 2000). The colloidal materials associated with turbidity provide adsorption sites for chemicals and biological organisms that may be harmful and cause undesirable taste and odour (WEC, 2008). Therefore, turbidity is one of the primary parameter for assessing drinking water quality (Parker et al., 2010). c. Suspended solids Solids in water can be in suspended or dissolved forms. Suspended solids in water can be observed with the naked eye. It consists of inorganic and organic materials, resulting from the erosive action of water flowing over surfaces. It is aesthetically displeasing; provide adsorption (attachment of particles to the surfaces or in the pores) sites for chemical and biological agents. Suspended solids may harbor disease causing organisms (Peavy et al., 1985).

d. Tastes and Odour
Drinking water should be free of taste and odour (Linsley et al., 1992). At the point of water usage, these two parameters should not be noticed (Sincero & Sincero, 2006). Tastes and odour are caused by organic decomposition of materials and volatile chemicals. They are aesthetically displeasing and odour producing substances may be carcinogenic (Peavy et al., 1985).  (Agunwamba, 2000). Decaying organic matter such as leaves, weeds impart colour to water which is objectionable not only for health reasons but for aesthetics as well (Sincero & Sincero, 2006). Coloured water is generally not accepted by people and is unsuitable for industrial uses and drinking.

Chemical Water Characteristics
Chemical water characteristics are mostly dissolve solids in water. It relates to the solvent capacity of a water source or sample. Chemical characteristics comprise organic and inorganic constituents, which are soluble and present in water. They include, total dissolved solids, alkalinity, hardness, fluorides, metals, organics and nutrients. Theses parameters are of a major and serious concern in water quality. Their degree in water determines the level of pollution or purity of the water source and suggest the water source suitability for human consumption without any impediment to health. a. pH pH is one of the most important operational water quality parameter which determines the suitability of water for various purposes with the optimum pH ranging from 7 -8.5. It determines the acidic and alkaline nature of water (Ramesh & Elango, 2006). Water with low pH (<6.5) could be acidic, soft and corrosive. The recommended level for human use is 6.5 -8.5. Above or below this stipulated range directly poses health risk and other secondary influences.

b. Electrical Conductivity (EC)
Electrical conductivity is the capacity of electrical current to pass through the water and it is directly related to concentration of ionized substances in that water (Singh and Khan, 2011). Excess of it reduces the osmotic activity of plants and therefore interferes with water absorption and nutrients from the soil. c. Total Dissolved Solid (TDS) TDS in water represent dissolve substances both organic and inorganic constituents soluble in water. It indicates the general nature and extent of contaminant in water (Ramesh & Elango, 2006). High level of TDS reflects higher dissolution of substances in the water. According to Linsley et al., 1992, total dissolved solids in a water sample is equal to 0.55 -0.7(conductivity value of the water).

d. Total Hardness
Total Hardness in water is primarily caused by the presence of calcium and magnesium, anions such as carbonate, bicarbonate, chloride and sulphate in water. Water with hardness above 200mg/l may cause scale formation in the distribution system, boilers and irrigation pipes (Ishaku et al., 2011). Water Hardness limits its use for domestic, industrial and agricultural activities. Hard water requires considerable amounts of soap to produce foam or lather. Hardness due to bicarbonate is called carbonate hardness generally known as temporary hardness, while permanent hardness are caused by non-carbonate ions (Parker et al., 2010). e. Alkalinity Alkalinity defines the capacity of water to neutralize acid (Nicholas, 2007). The measurement of alkalinity and pH is needed in drinking water. Parker et al., (2010) stated that Alkalinity measurement is important to determine water stability. It equally imparts a bitter taste to water (Peavy et al., 1985) f. Cations Cations include Calcium (Ca 2+ ), Magnesium (Mg 2+ ), Sodium (Na + ), Potassium (K + ), Iron(Fe 2+ ), Manganese(Mn 2+ ), Aluminum, etc. Some of the substances are introduced to aquifers by rainwater. Dissolved Calcium and Magnesium in water are the two most common minerals that make water hard. The hardness of natural water varies considerably. Sodium is a nontoxic metal abundant in earth crust, highly reactive and found in natural waters. High concentration in water can cause a bitter taste and as well pose health risk to kidney and cardiac patients (Peavy et al., 1985). Iron is found naturally in water, soil, rocks and can also be released in water through other man-made activities such as in industrial wastes, corrosion of metals containing iron, refining of iron ore, etc. It can be present in soluble and insoluble form known as ferrous and ferric iron respectively. Drinking water containing ferrous iron can be colourless and clear which render water turbid when exposed to air resulting in a precipitate called ferric iron (Agunwamba, 2000). For good health, average concentration level is needed. However, excess of it, can damage blood vessels, kidney, liver and can even cause death (SIC, 2007). Manganese and iron impart brownish colour to water and are therefore objectionable (Sincero & Sincero, 2006). Their concentration in water determines the amount of organic matter present (Agunwamba, 2000). Excess concentration level of manganese in drinking water can led to neurological disorder (NIS, 2007). Potassium is an essential water parameter that is not often found in drinking water, at concentration that may pose health risk. However, intake of excess potassium can result in kidney problems, diabetes, hypertension, heart diseases and may also cause immature kidney functions in infants (WHO, 2009) g. Anions Anions include bicarbonate (HCO3 -), sulphate (SO4 2-), chloride (Cl -), nitrate (NO3 -), phosphate (PO4 3-) and fluoride. They are introduced to aquifers through rainwater (Younger, 2007). They are beneficial in irrigation practices especially in the presence of calcium (Nas, 2009). High concentration of chloride indicates high degree of pollution (Bartram & Balance, 1996). Sources of Chloride in natural water may include sewage discharges and industrial effluents, dissolution of salts deposits, oil well operations. Nitrates occur naturally in water due to break down of organic compounds containing nitrogen in oxygen presence (Gama, 2017). High level of nitrogen in water is directly linked with agricultural activities involving excessive use of fertilizers (Perera et al., 2014), fertilizer manufacturing industries, leakage of sewage systems into water bodies, etc. It can be naturally removed from water through denitrification process. Phosphate is mostly used in fertilizer for soil supplement and is released into surface water through runoff. Fluoride is associated with sedimentary or igneous rock, seldom found in small quantities in ground and surface water. High concentration in drinking water causes discolouration of teeth, bone fluorosis and other skeletal abnormalities (Peavy et al., 1985).

h. Heavy Metals
Heavy metals such as barium, arsenic (As), lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr), zinc (Zn), nickel (Ni), copper (Cu), and silver, etc. are very toxic and poisonous in small or low concentrations to both human and aquatic organisms. They are hazardous even in very minute concentrations thus posing serious health risk (Peavy et al., 1985). Arsenic is colourless, tasteless and odourless in water and can be found naturally in water and soils through weathering actions (Srivastava, 2015). Zinc and Copper in synergy may be toxic to biological species in small amount (Peavy et al., 1985) DRINKING WATER QUALITY STANDARDS Drinking water quality standards are standards set to ensure the protection and safety of human health in regard to water consumption (NIS, 2007). The advancement of knowledge of the nature and effects of various contaminants in water has brought about regulatory bodies setting recommended (maximum allowable) limits for each water parameter especially water desired for drinking purposes. The quality of water is assessed and evaluated based on the concentration level or degree of these parameters in water (WHO, 2003). The quality of water is regarded as satisfactory when the concentration level of parameters investigated are less than the maximum allowable limits. These recommended standard limits are set based on their implication on human health. Excess of the recommended or allowable limits is a strong indication of health risk for consumers. World Health Organization (WHO) guideline is a backbone from which other regulatory bodies adopted their guideline (Peavy et al., 1985) Nigerian Standard for Drinking Water Quality (NSDQW) was also established to ensure the protection of consumers in Nigeria. This standard sets maximum allowable limits of drinking water parameters in Nigeria anchored on WHO guideline. The Nigerian Standard for Drinking Water Quality covers all drinking water except mineral water and packaged water. The standard applies to drinking water supplied by state water agencies, community water systems; water vendors and water tankers; public or privately owned establishments, privately owned drinking water system and use solely for the family residence (NSDWQ, 2007). . One of the United Nation goals is to ensure clean water and sanitation of which importance has been revealed by Covid 19 pandemic. According to United Nations, nearly 1,000 children die due to preventable water and sanitation-related diarrheal diseases (UN, 2015). The health effect of chemical substances consumed through drinking water manifest after a prolonged exposure and accumulation which conversely hide the potential source of exposure. Kidney failures, liver and cardiovascular diseases are woven with consumption of contaminated food, drinks and water. However, some of the guidelines and standards for drinking water are established as basis for the protective and precautionary measures to be taken against adverse health impacts of these water parameters on human and environment at large (WHO, 2021). The degree of the presence of these contaminants is determined by laboratory analysis aimed at providing a consensus description of the water quality. Table 1 is the summary of diseases on human beings as a result of consuming contaminated untreated water sources harbouring micro-organisms. Table 2 reveals the maximum allowable limits of physical and chemical water quality parameters set by NSDWQ, WHO and EU as well the health impact, if the recommended limits are exceeded.   (Kandora,2020; UNICEF,2020). It spreads when respiratory droplets from an infected person get into the nose, eyes or even mouth of people close by. It can also be contacted when people touch surfaces that are contaminated with the virus and without washing their hands, touch their mouth, nose or eyes. It may actually survive on surfaces for few hours to several days, although disinfectants can kill it (Kandora, 2020). It is referred to as a pandemic because of its global spread and lack of people's immunity. According to NCDC (2021), 164,756 cases have been confirmed, 154963 cases have been discharged and 2,062 deaths have been recorded in 36 states and the Federal Capital Territory. This infection and spread can be prevented when people have access to clean water and regularly engage in hand washing for at least 20 seconds with soap and water or use an alcohol based sanitizer (NCDC, 2021). Wearing of nose masks and safe distancing are also preventive measures to avoid contracting the virus. Touching of eyes, nose or mouth should be avoided. Stay at home and also seek medical attention when unwell and exhibiting symptoms.

CONCLUSION
The presence and level of physical, biological and chemical constituents in water referred to as water parameters determine its suitability for drinking purpose. Biological parameters in drinking water sources and supply can directly or indirectly impair the use of that water for human consumption. Their presence in drinking water outside health risk can also cause other problems such as aesthetic and technical problems e.g., corrosion in pipes (Boe-Hansen, 2002). To overcome these problems and challenges, it is therefore imperative that drinking water sources should be tested for specific pathogens that can endanger human health. Detection of some bacteria signifies faecal contamination of water sources and presences of enteric pathogens. These pathogens give rise to outbreaks of water related diseases. One of the measures enlisted by NCDC in control of infectious diseases is to ensure that drinking water are boiled, filtered and properly preserved or stored safely in a very clean container (NCDC, 2020).
Physical water quality parameters are more or less for aesthetical consideration and an indirect indication of level of dissolved constituents present in the water.
Chemical water quality parameters predominate and as such directly determine the level of pollution or purity of water for human consumption. The complexities of water quality can be simplified in understanding of these parameters and their contaminated or pollution index that are not permitted in drinking water. A critical concern must be observed especially to some water quality parameters needed in human body at some profitable level such as iron, sodium, fluoride. Of course, excess of such parameters have also been seen