This paper discussed the application of water quality index for the assessment of selected water quality parameters within the Apo resettlement area of the Federal Capital Territory, Nigeria. The Apo resettlement area, a semi-urban residential settlement has since seen a rapid urbanization following the creation of Abuja as the new administrative capital of Nigeria on 3rd Feb 1976. This is through the promulgated Federal Capital Territory decree No. 6, 1976 resulting from the growing unsuitability of Lagos as Nigeria’s Federal Capital City. Water quality index (WQI) provides a single number that expresses the overall water quality, at a certain location and time, based on several water quality parameters. The water sourced from the Apo resettlement area was rated as a good water type with index of 76.0% by World Health Organization permissible limits, whilst the Federal Ministry of Environment (FMEnv Limit) rates it at 45.6%. The study outlined that the surface water of the area is impaired due to the rapid urbanization and is not suitable for domestic consumption without treatment. However, the water body is suitable to support ecosystem functioning. This can be improved, or level of pollution reduced if proper measures are put in place to discourage the users from polluting the water in order to bring about improved health.