Incident of water-borne diseases is becoming more rampant in developing countries in the 21^st century. This paper examines the contamination levels of some selected wells in Ogbomoso South Local Government Area (LGA), Oyo State, Nigeria. Methodology includes administering of structured questionnaire, field survey/sampling and laboratory analysis. The first set of questionnaires sought information on water sources, quality, supply and treatment. These were administered in 10 selected major locations which included: Ajegunle, Arinkinkin, Arowomole, Caretaker, Esanu-Aje, Ita-Olola, Malete, Oke-Alapata, Ora-Gada and Sunsun. The other set which was administered in 6 randomly selected Health Institutions viz: Oyo State General Hospital, Alaafia Tayo, Oore-Ofe, Bethel, Favour, and Grace Hospitals had questions on health-related issues. Ten (10) wells were randomly selected for sampling, one in each location. Results were compared with WHO’s Drinking Water Standards. Questionnaires revealed that residents depended mostly on wells for water supply; the water quality was low; supply was irregular; quantity was inadequate and boiling was the commonest treatment method. Health Officials established that some residents consumed improperly treated well water and there were some incidences of water-related diseases. Laboratory analyses showed that samples from Ajegumle and Esanu-Aje had colour values above the standard. Also, the pH was observed to vary from slightly acidic to slightly alkaline with values ranging between 6.0 and 8.1. Only Arinkinkin and Ita-Olola areas had permissible values of total alkalinity and Oke-Alapata had the highest chloride value of 400 mg/l while the highest nitrate concentration was at Esanu-Aje (127.58 mg/l). Study concludes that water supply in the area is not fully supportive to health. To abate the problem, it is recommended that aside boiling, each household should endeavour to coagulate, filter, soften and disinfect well water before consumption. Also, personal hygiene within each household must always be emphasized and improved upon.