Water Quality From Hand-dug Wells and Boreholes at Micheweni District of Pemba Island - Zanzibar

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The State University of Zanzibar (SUZA)
Water supply systems and drinking water inaccessibility in developing countries is a global concern that calls for immediate action. About 884 million people in the world still do not get their drinking water from approved sources, and almost all of these people are in developing regions. Therefore, the primary objective of this study was to determine the water quality from hand-dug wells and boreholes at Micheweni- district of Pemba Island, Zanzibar. Water samples were collected from 24 hand-dug wells and boreholes during dry season (December, 2015) and wet season (April, 2016). The analysis was done according to standard methods for water examination and reported based on the WHO prescribed limit for drinking water and TBS standard. Total and faecal coliform were enumerated using the membrane filtration technique. Some physico-chemical parameters (pH, conductivity, turbidity, TDS) were determined using multiparameter water quality meter. Phoshate, chloride, nitrate and sulphate were also measured using bench photometer method and heavy metals (Cd, Pb and Fe) were analyzed using atomic absorption spectrophotometer (AAS). The well water from all the wards within the community did not meet the WHO guidelines for drinking water (zero faecal and total coliforms) except water from Shumba Nguuni and Makangale Sokoni. Lead and cadmium were not detected in all water samples. The highest concentration of iron is found at Maziwa Ng‘ombe Kibagoni with (1.09 mg/L). The revealed showed that the highest EC, TDS and turbidity were found at Msuka Taponi with (1751 μS/cm, 901 mg/L and 48.9 NTU), respectively. High amount of turbidity, this may be due to poor filtration process of water supplies as well as human activities including logging, agriculture, which contributed to periodic pulse or chronic levels of suspended sediment in water may have effects on the water sources. In addition, explanation for high turbidity is the use of a hand pump resulting from corrosion. The following data analysis showed highest levels of Total coliform at Shuma Nguuni (SH3) 98 cfu/100 mL. . A maximum level of faecal coliform was found at Msuka Ungi (32 cfu/100 mL). Highest levels of coliform were likely influenced by distance from latrines. Moreover, the highest concentration of nitrate was found at Konde Chanjaani with (12.2 mg/L). The high values of nitrate could be attributed to the presence of manure spill, fertilizer application, wastewater, sludge, and septic tank systems, which are the main contributors to nitrate concentration in water. In addition, high concentration of chloride was found at Mziwa Ng‘ombe Kibagoni (771.4 mg/L). Thus, high amounts of chloride in these sampling sites might be due to natural processes, such as the passage of water through natural salt formations in the earth by intrusion most these wells are near to the sea or it may be an indication of pollution from sea water. Chemical analysis showed that the concentrations of some parameters in the drinking water samples from the research region were above the permissible limits of the WHO and TBS standard for drinking water quality guidelines. Iron, chloride, phosphate, EC, turbidity, faecal and total coliform was found to exceed WHO and TBS maximum limit. Thus, consumption of water from sampled groundwater sources without proper treatment might cause serious ill effects. Therefore, there is a need of attention for the ZAWA and other stakeholders to undertake regular checking sources of water used for drinking purposes to protect public health.
Available in print form, Tunguu Reference Library
1. Water quality from hand-dug well - Zanzibar 2. Water quality from boreholes - Zanzibar