The poor state of sanitary services is a major environmental challenge in urban centres of Nigeria. The situation has reached a crisis proportion in the absence of basic sanitary services like modern toilet, good sewage management method, functional drainage system, good roads, environmentally- friendly solid waste disposal method, potable water, electricity and social amenities. The aim of the study is to show how infrastructural improvement method of slum rehabilitation can be applied to reduce costs for improving environmental quality of a major slum area in Yenagoa. Basic Research Methodology was applied using questionnaire, direct observation and personal interview techniques to collect data. Both qualitative and quantitative techniques were applied to analyse data through the use of tables and charts. The findings in the study showed that poor condition of sanitary services seriously degrades the environmental quality of the study area. The standard of living in the area is very poor as the people lack access to basic sanitation and social amenities. It showed that only 2% of the households exclusively use water closet (wc) toilet; 4% have well-maintained septic tanks; none of the houses are on road with functional drainage system; 10% of the houses are on tarred roads of 10 or more metres right-of-way and none of the households use environmentally-friendly solid waste management method.