Ground water quality monitoring in Makuyu division of Muranga District

Abstract

This report shows results of groundwater quality monitoring in Makuyu division of Maragua district. Analytical results have revealed that the 21 boreholes and wells water are not polluted and can be consumed readily. In the ground water quality monitoring water samples were obtained from 21 boreholes and wells. In addition, water from three rivers in the area were sampled and tested to compare their quality with that of the groundwater. The depth of the boreholes and wells were divided into three categories. These were 0-50 metres, 50 - 100 metres and above 100 metres. The borehole and wells are distributed over the area. The physical properties monitoring indicate that the temperature, conductivity, turbidity, colour, dissolved solid, suspended solids and total dissolved solid were within the WHO guidelines and Kenya Bureau of Standards limits except for dissolved and total solids for Kamahuha girls high school borehole, which has 4290 mg/1. The physical properties values ranges from 22 °C - 24 °C for temperature, 48 - 6130 Us/cm for conductivity, 0.9 - 38 FTU for turbidity and <5 - 20 UH for colour, 182 - 4290 mg/1 for dissolved solids and total solids. For the river waters, the values ranged from 150- 195 Us/cm for conductivity, temperature is 22 llC, 41-85 FTU for turbidity, 30 - 70 °H for colour and 1109 - 4179.8 mg/1 for dissolved solids and total solids. y The groundwater quality was chemically good. The pH range between 6.39 and 7.97 for boreholes and wells, while for rivers it ranged from 7.06 - 7.34 which are within the World health Organisation Guidelines (WHO, 1993). The concentrations of fluoride ions in most of the sources were within the recommended limits except for Makuyu Secondary School borehole, which had 2.5 mg/1. The chemical properties monitoring indicated that the concentration of iron, manganese, copper, zinc, selenium, titanium, strontium, yttrium and zirconium showed no significant heavy metal pollution in groundwater. The trace metal concentrations values ranged from 0.0994 - 1.1450 mg/1 for iron, 0.0046 - 1.0190 mg/1 for manganese, 0 - 0.0588 mg/1 for titanium, 0.0011 - 0.0142 mg/1 for copper, 0.0027 - 0.1692 mg/1 for zinc, 0.0011 - 0.0016 mg/1 for strontium, 0.0012 - 0.0043 mg/1 for yttrium, and 0.0013 - 0.0043 mg/1 for zirconium. v Groundwater Quality Monitoring in Makuyu Division of Maragua District In addition, the concentration of other parameters like chloride, calcium hardness, total hardness, total alkalinity, carbonate, fluoride, sulphate, phosphate, nitrate, and dissolved oxygen were also below the maximum permissible limits for drinking water as given (WHO 1993). Pesticides presence in water was not detected. The biological monitoring indicated that human being or animals pollute few of the groundwater sources. The presence of feacal coliforms in some of the wells indicated biological pollution. The total coliform/100mg/l values ranged from 0 - 2500 and total feacal coliform/100mg/l values ranged from 0 - 8000 for boreholes and wells. For the river water, the total coliform/100mg/l values ranged from 100 - 600 and total faecal coliform/100mg/l values ranges from 30 - 248. Indicating the river water will need full treatment before consumption. The deep boreholes and wells had good water quality except three boreholes. The Kamahuha Girls Secondary School borehole, Wamtega borehole and Gichuiri well, which are located within Sabasaba town. The water from these sources had high levels of total solids. In addition, Ndachi Mugo’s well, Kamahuha well and Muruithia’s well had high level of feacal coliforms/ 100mg/l ranging from 1000 - 8000 total faecal coliform/lOOml. These boreholes were all located near pit latrines. Thus to prevent presence of feacal coliforms in the groundwater, the wells should be located away from pit latrines and flash floods should be diverted away from the wells. Secondly, the bucket used to draw water from the wells should be clean.