Groundwater is now heavily relied on in Lagos metropolis as an alternative source of water where surface water is seriously
polluted. This is because of the increasing industrialization and population explosions. The continued reliance on ground
water has resulted in its decline in quantity and quality. In this study, the coastal aquifers of Lagos metropolis were selected
for an assessment of its groundwater quality and impact of saline intrusion
Thirty water samples were collected each from hand dug wells and boreholes in six different locations in the studyareas.
These include: Ikeja, Lagos Island, Ajah, Victoria Island, Eti- Osa and Yaba. The chloride concentrations ofall the samples
were acquired and then compared with the World Health Organization (WHO) standards for chloridecontent in drinking
water. We selectedhand dug well and borehole becausethey are the common source of drinking water in the areaunder
consideration. Results show that the average chloride concentrations in all the samples collected from hand dug well in all
the six locations exceed the WHO value of 250mg/l (value recommended for safe drinking water) with Ajah havingthe
highest Chloride concentration of 606.68mg/l and Ikeja with the least value of 255.37mg/l. For the water samples from
boreholes, only one of thesamples showshigh chloride levelabove the WHO standard range.The highest chloride value
observed was 343.3mg/l while the lowest was 15.84mg/l.
This indicates thatborehole water in the considered areas is safer for drinking than that of hand dug wells.