Assessment of Drinking Water Quality from the Malakisi River in Western Kenya

The scarce water resources globally are being polluted by mainly human activities, making accessibility to clean water a major challenge due to the high cost of conventional water treatment methods and lack of frequent monitoring of pollution levels. A study has been done on Malakisi to establish its quality. Coliforms, chemical oxygen demand (COD), biological oxygen demand (BOD), fluorides, pH, conductivity, total hardness, nitrates, phosphates, sulphates, turbidity and heavy metals (Zn, Cu, Mn and Fe) were analyzed. For Coliforms, endo agar media were carefully prepared and placed in an incubator upside down and set at 44^oC for faecal coliform and 37 ^OC for total coliform and then left for 24 hours in the thermostat and results recorded as cfu/100 ml. COD was measured by mixing 2 ml of each sample with the low range reagent mixture of K₂Cr₂O₇, AgSO₄, HgSO₄ and H₂SO₄ and the mixtures tested in a COD reactor, which was already set at a temperature of 150^OC and left for 2 hours. For BOD, the BOD Track test procedure was used. Fluoride was analyzed using the SPADNS method while pH was determined by the potentiometric method using digital pH model sension-51938. The conductivity meter was used to measure conductivity. Total hardness was determined using the colorimetric method at a wavelength of 522 nm. A 1.0 ml of Ca and Mg indicator was added to 100 ml of the prepared sample followed by one drop of 1 M EDTA solution. Total   hardness was the sum of mg/l Ca as MgCO₃ plus mg/l Mg as CaCO₃. Total nitrogen, phosphates and sulphates was determined by Hach spectrophotometer DR/4000 at wavelengths of 400 nm, 890 nm and 450 nm, respectively. For turbidity, 5 ml of sample was poured into the Pocket Turbid meter and turbidity measurements were recorded in nephelometric turbidity units. The levels of heavy metals were determined using a UV- spectrophotometer, Hach DR/4000. The following concentration levels of the pollutants  were established in river water: Zn (0.3 mg/l), Cu (0.08 mg/l), Mn (0.3 mg/l) , Fe (0.61 mg/L), coliforms (38 Cfu/100 ml), pH (7.1), NO₃^- ( 0.28 mg/l), PO₄^3- (0.43 mg/l), SO₄^2- (0.545 mg/l), F^- (0.40 mg/l), BOD (13 mg/l), COD (26mg/l), turbidity (124 NTU), total hardness (2.30 mg/l) and conductivity (204 μs/cm). From the results, all the parameters analyzed were within the WHO required limits except coliforms, turbidity, Mn, Fe and Cu which were found at levels higher than the WHO maximum required limits. The Malakisi river is thus polluted and preliminary treatment of the water is required. Coagulation of the water by adding alum, chlorination, boiling, use of solar powered water filters or purifiers and creation of buffer zones along the river system to allow growth of river line macrophytes are some of the measures that could help improve the quality of water.