Three types of sachet water samples and three types of borehole water samples all from Owerri Municipal, Imo State were collected and analyzed for physicochemical parameters. A total of twenty (21) parameters including Odour, Colour, pH, Conductivity, Acidity, Alkalinity, Total Solids, Dissolved Solids, Suspended Solids, Dissolved Oxygen (D.O), Chemical Oxygen Demand (C.O.D), Calcium, Copper, Iron, Manganese, Lead, Chloride, Nitrate, Zinc, Magnesium and sulphate were analyzed. The W.H.O recommended standards shows that all the samples are odourless and colourless. Borehole water is 7.1 in pH, while sachet water has a lower value of 6.5. Acidity in sachet water has a mean value of 50mg/l while borehole water has 54mg/l. Total solids of borehole water is higher with a mean value of 15.6mg/l, while sachet water has 5.7mg/l. Alkalinity is higher in borehole water with a mean value of 165, while sachet water has a lower value of 113. Dissolved oxygen in borehole water has a higher value of 1.19mg/l than sachet water with a value of 0.83mg/l. C.O.D is trace in all the samples. Suspended solids in borehole water is 1.02mg/l which is higher than sachet water which has 0.62mg/l. Calcium is higher in borehole water with a value of 3.1mg/l, while sachet water has 1.92mg/l. Copper content is higher in borehole with a value of 1.42mg/l in borehole water, while sachet water has 0.49mg/l. Chloride is higher in sachet water with a value of 64.1mg/l and lower in borehole water 56.2mg/l. Manganese and Lead values of borehole water are 0.54mg/l and 0.77mg/l respectively, which are higher than W.H.O standard, while sachet water has values of 0.28mg/l and 1.01mg/l. Iron value of borehole water is 1.20mg/l, while sachet water is lower with a value of 1.12mg/l. Nitrate is 0.39mg/l in borehole water which is lower than sachet water which has 0.41mg/l. Borehole water is lower in Zinc with a value of 0.41mg/l while sachet water has a higher value of 0.44mg/l. Borehole water has a phosphate value of 5.21mg/l while sachet water has a lower value of 4.02mg/l. Magnesium is higher in borehole water with a value 1.47mg/l, while sachet water has 0.93mg/l. The parameters analyzed most generally conform to the W.H.O standards for drinking water.
Water is a universal solvent, which consist of hydrogen and oxygen atoms. Chemically, it could be defined as a chemical substance with two atoms of hydrogen and one atom of oxygen in each of its molecules; hence the molecular formula is H2O. It is formed by the direct reaction of hydrogen with oxygen;
2H2 + O2 2H2O
Water is colourless, odourless and tasteless liquid in its pure form. It is an inorganic substance that occurs in three states; liquid gaseous and solid states1. Water covers 71% of the earth surface. On earth , it is found mostly in oceans and other large water bodies with 1.6% of water below ground in aquifers and 0.001% in the air as vapour clouds (formed from the solid and liquid water particles suspended in air), and precipitation2. Oceans hold 97% of surface water, glacier and polar ice cap 2.4% and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earths water is contained within biological bodies and manufactured products. Water on earth moves continually through a cycle of evaporation, transpiration, precipitation and runoff, usually reaching the sea. Overland, evaporation and transpiration contributes to the precipitation. Clean and fresh drinking water is essential for human and other life forms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world3, 4. There is a correlation between access to safe water and GDP, per capita5. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability6.
As water is heated from OOC, it contracts until 4oC is reached and then begins the expansion which is normally associated with increasing temperature. The viscosity of water decreases ten folds as the temperature is raised from OOC to 100 OC, and this also is associated with the decrease of ice like character in the water as the hydrogen bonds are disrupted by increasing thermal agitation. The electrical conductivity of water is at 1,000,000 times larger than that of most other non-metallic liquids at room temperature. The current in this case is carried by ions produced by the dissociation of water according to the reaction;
H2O H+ + OH-
These products recombine completely to form water vapour, also undergoes most of the chemical reactions of liquid water and at very high concentration even shows some of the unusual solvents properties of liquid water. Above 3740C, water vapour may be compressed to any density without liquefying, and at a density as high as 0.4glcm3, it can dissolve appreciable quantities of salt7.
1.1 SOURCES OF WATER
Water naturally exists in three main sources; rain water, ground water and surface water.
Rain water is naturally the purest source of water but as it gets down it absorbs compounds from the atmosphere. Its main components are chlorides, nitrates, sulphates, sodium, potassium and ammonia. The concentration can vary from 0.1 to 10uglml. The rain can be collected from roofs and prepared water sheds which could assist in polluting and making it one of the most unfit sources of water for drinking8.
Ground water are said to have emanated from the melting of meteoric water (rain, snow, and hailstone), into the ground, they have served as source of domestic water supply. It offers cheaper and purer supply. The main ionic components are chloride, nitrate, sulphates, potassium, sodium and calcium. This includes natural springs, wells and boreholes9. As it percolates into the earth it is subjected to some purification actions by the numerous chains of pervious and impervious rock strata or layers. Because of the disintegrating and dissolving power of water, it dissolves some of the rocks which make up the earth layers making it to have impurities like oxides, nitrate, sulphates, calcium, iron, magnesium9. Some level of purity is achieved on turbidity, colour, odour and taste. It reaches surface through wells, shafts, springs, borehole.
The oceans hold about 97% of earth’s water. More than 2% is locked up in ice in the polar caps, and over 75% of the fresh water of the world is ice of the 1% of the liquid fresh water. Some is ground water at depths of over 1000 feet and impractical to obtain, and only the very small difference, possibly 0.6% of the total water of this planet is ever available to man as it cycles sea to atmosphere to land to sea.
Surface water includes streams, ponds and lakes, its main ionic compounds include chlorides, nitrates, sulphates, magnesium and calcium. The concentration of components here are more than those in rain water and ground water. Sea water could be considered as surface water. The salt content in it is so much that it cannot be used as drinking water because it would take the body a lot of work to flush out excess salt before usage for metabolism, it is also inadequate in the machinery use as it rust machines, it kills most crops frequently carry suspended solids10.
Water can dissolve many different substances giving it different taste and odour. In fact, humans and other animals have developed senses to be able to evaluate the portability of the putrid swamps; and favour the pure water of the mountain, spring, and aquifer. Humans also tend to prefer cold water rather than lukewarm, as cold water is likely to contain fewer microbes. The pleasant taste associated with spring water or mineral water is derived from the minerals dissolved in it, as pure water is tasteless.
1.2 IMPORTANCE OF WATER
Water is an indispensable rain material for a multitude of domestic and industrial purpose. Water is the most abundant material, its cheap production with less than 500ppm impurities will be more important to the world than atomic energy, as we all know it today. Water plays an important role in the world economy as it functions as a solvent for a wide variety of chemical substances and facilities industrial cooling and transportation. Approximately 70% of fresh water is consumed by agriculture11.
Domestic uses of water includes; cooking, washing of clothes, cars, dishes, to shower, flushing away of wastes and drinking. The human body contains 55% to 78% water depending on body size12. To function properly, the body requires between one and seven litres of water to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity and other factors. Most of these are injected through foods or beverages other than drinking water directly. It is not clear how much water intake healthy people need, though most advocates agree that 6-7 of glasses of water daily is the minimum to maintain proper hydration13.
Water is used for fighting wildfires. Water has a high heat of vaporization and is relatively inert, which makes it a good fire extinguishing fluid. The evaporation of water carries heat away from the fire. However, water cannot be used to fight fires of electric equipments because impure water is electrically conductive or of oils and organic solvents, because they float on water and the explosive boiling of water tends to spread the burning liquid. Use of water in fire fighting should also take account the hazards of a stream explosion, which may occur when water is used on very hot fires in confined spaces, and of a hydrogen explosion, which may react with water, such as certain metals or hot graphite, decomposed the water producing hydrogen gas.
Water is used in biochemical processes, it is central to photo synthesis and respiration. Photosynthetic cells use the sun’s energy to split off water molecule (photolysis of water) to form hydrogen and oxygen.
2H2O 4H + + 4e- + O2
Hydrogen is combined with CO2 (absorbed from air or water) to form glucose and released oxygen. All living cells use such fuels and oxidized the hydrogen and carbon to capture the sun’s energy and reform water and CO2 in the process (cellular respiration). Water is also central to acid-base neutrality and enzyme function. An acid, a hydrogen ion (H+, that is a proton) donor can be neutralized by a base, a proton acceptor, such as hydroxide ion (OH-) to form water. Water is considered to be neutral, with a pH (the negative log of the hydrogen ion concentration) of 7. Acids have pH values less than 7 while bases have values greater than 7.
In agriculture, the most important use of water is for irrigation, which is a key component to produce enough food. Irrigation takes up to 90% water withdrawn in some developing countries14 and significant proportions in developed countries, (United State 30% of fresh water usage is for irrigation15).
Water is widely used in chemical reactions as a solvent, dissolving many ionic compounds. In organic reactions it does not dissolve the reactants well and is amphoteric (acidic and basic) and nucleophilic.
In recreation, water can be used for many purposes as well as for exercising and for sports. Some of these include swimming, boating, surfing and diving. In addition, some sports like ice hockey and ice-skating are played on ice. Lake sides, beaches and water paths are popular place for people to go, relax and enjoy recreation. Humans also use water for snow sports like sledding, snowboarding, which requires the water to be frozen.
Industrial uses of water includes; cooling of machinery in power plants, condenser cooling, sanitary services and for boilers. Many industrial processes rely on reactions using chemicals dissolved in water, suspensions of solids in water slurries or using water to dissolve and extract substances.
Water is used in power generation. Hydro-electricity is electricity obtained from hydropower. Hydroelectric power comes from water driving and water turbine connected to a generator. Hydroelectricity is low-cost, non-polluting, renewable energy source. The sun supplies the energy. Heat from the sun evaporates water, which condenses as rain at higher altitudes from where it flows down. Pressurized water is used in blasting and water jet cutters. Also very high-pressure water guns are used for precise cuttings. It works very well; it is relatively safe and not harmful to the environment. It is also used in the cooling of machinery to prevent overheating as in vehicle radiators.