The physical test result of Asella municipality water had shown that colourless, odourless & tasteless which meets WHO standard for drinking water had similar status for stated water quality indicators.
The turbidity measurement value was greater than WHO standard value of 5NTU.the test result of the first site was maximum, this may indicate you the need for treating effectively Ashebeka river water. The other remaining test result had turbidity values raise over WHO standards, this might be, even though treatment plant of Asella municipality works effectively the availability indicates treatment plant & water reservoir have to wash to reduce further turbidity substances. Water turbidity is very important because high turbidity is often associated with higher level of disease causing microorganism, such as bacteria and other parasites(21). Similar study in Nigeria turbidity value ranged 0.77-0.99 NTU(22), which was lower than Asella town municipality water supply from Ashebeka river.
The total dissolved solid was substances that were found dissolved form in water sources. (23) TDS are composed mainly of carbonates, bicarbonates, chlorides, sulphate, calcium, magnesium, phosphate, nitrate, sodium, potassium, and iron. The TDS is the term used to describe the inorganic salt and small amount of organic matter present in solution or water.
The principal constituents are usually calcium, magnesium, sodium and potassium metals, carbonate, hydrogen carbonate, chloride, sulphate and nitrate anion(24) . It has been reported that drinking water with extremely low concentration of TDS may be unacceptable because of its flat insipid taste(24, 25).
The highest value was recorded in Asella hospital water sample site. This may be due to solid settled in hospital water reservoir might be not washed with the appropriate time interval. The ISI standard for dissolved solids (23)is up to 500 mg/lit and the maximum permissible quantity is 1500 mg/lit(26). The sample test result with current study all were with the range of WHO & ISI standard of drinking water. Similar study done in Nigeria had found for total dissolved solid ranged 250-700mg/L (27)But the result of this finding ranged 34.4-76.6mg/L which was lower than the previous study. Total dissolved solids is an indication of dissolved metals in water(28).
The important test result was detected out fluoride & aluminum tests. The aluminum concentrations raise up above WHO standard 0.2mg/L at site two, three, four & five. This might be due to high dose of alum utilization by Asella water & sewerage authority office for coagulation process.
The total hardness result was lower than WHO standards 500mg/L(24). Water hardness in Asella water of Ashebeka river was grouped under soft water. Total hardness of water is due to the presence of bicarbonate, sulphate, chloride, and nitrates of Ca and Mg(29). Similar studies in Tanzania of temeke river ranged 50-710mg/L(30) The finding of this study lower than temeke rivers. According to ISI, the acceptance limit of total hardness (as CaCO3) is 200 mg/lit which can be extended to 600 mg/lit(31). Ca++ & Mg++ are important ions contributing towards total hardness. Hardness has no known adverse effects. Hardness above 200 mg/lit of water is not suitable for domestic use in washing, cleaning and laundry(31).
The acceptable limit of Ca++ & Mg++ for domestic use is 75 mg/L & 200 mg/L respectively. Calcium & magnesium have important function for bone growth. Researches and studies proved that water with low magnesium can cause increased morbidity and mortality for cardiovascular disease, higher risk of motor neuronal disease, pregnancy disorders and preeclampsia. Water with low in calcium may be associated with higher risk of fracture in children, certain neurodegenerative diseases, preterm birth and low weight at birth. Lack of both calcium and magnesium in water can also cause some types of cancer(30).similar studies in India ranged 32-98mg/L for calcium & 10-89 mg/L for magnesium study done on Uttarakhand river(32). The finding of this study was too much lower than with Uttarakhand River. The stated metal analysis results of this study were found below WHO standard for each specific metal analysis.
The WHO standard for fluoride concentration is 1.5mg/L. the result of this investigation in all sites was below this standard. Low fluoride centration causes tooth decay. Similar study on boreholes in Nigeria ranged 0.13-0.92 mg/L(22), which was higher than Asella municipality water supply. This indicates that ground water had greater fluorine concentration than river water.
Use full water quality test like alkalinity & electrical conductivity tests were performed, but the result was below WHO requirements which did not affect the health the costumers.
The WHO standard for dissolved oxygen 6.5mg/L & any value above this is acceptable for drinking water quality(33). But this study result had found only at site three near stated WHO standards, while the other site needs dissolved oxygen correction for accuracy. This might be Asella town water treatment plant had no aeration chamber. Similar study Wukro river water dissolved oxygen ranges 3.54-11.8mg/L(34).
The WHO standard for BOD & COD test standards 2mg/L & 50mg/L respectively(33). The test results for BOD & COD were above WHO standards at site one & site eight. This might be due to the water carrying pipe carried dissolved substances because of universal character of water & settled solid within pipe lines increase the concentration of stated water pollutants. The remaining test results were below WHO standards not affecting water quality. Similar study in Wukro river water ranges 2.5-6.6mg/L & 3.2-12.8 mg/L of BOD & COD respectively(34). The Asella municipality water result was higher than Wukro River.
The bacteriological analyses were carried out by the detection of coliform & E.Coli count tests. Both results had shown that the tests were above WHO standards before the treatment plants. The results show very high microbial counts for the various drinking water samples when compared with the WHO(24) standard of 1.0 × 102 CFU/ml. For those tests which had taken after the treatment plants the tests for fecal coliform & E.Coli tests were negative which lies with the range of acceptable standards. Similar studies in Nigeria(35) water supply the total coliform count bore holes 10-15MPN/100ml, which were lower than Asella municipality water supply before the treatment plant.
The ammonia concentration throughout the study sites above the WHO standards of 0.05mg/L. This may be due to the occurrence of organic pollution after water treatment plants. The presence of nitrite concentration above WHO standards 0.5mg/L at station five might be indication of pollutants appear after treatment plants may have health effects.
The statistical significance test result had shown that the pollution load may had a contribution for increasing the variety level of water pollutants due to natural & man made factors.