Access to water and sanitation are critical components of public health and socio-economic development, as well as pointers to the fulfillment of Sustainable Development Goal 6 (clean water and sanitation). This review paper presents a critical assessment of the situation and challenges facing access and availability of water/water sources and their sanitary conditions. Considering that Nigeria is the most populated black race, the significant government efforts and international interventions made in the area of water, sanitation, and hygiene, many communities are still lacking access to safe water and adequate sanitation facilities. The research observes that about 70% of Nigeria’s population has access to water but more than half of the sources are contaminated thus reflecting the current challenges facing Nigeria’s water and sanitation sector. Some of the challenges highlighted include overpopulation/urbanization, poor government funding and investment, absence of solid waste management systems, and climate change/variability amongst others. Positive recommendations such as investment by government agencies to provide funding, private-public partnerships to enhance/expand existing infrastructure, public awareness on water usage and sanitation, and provision of water regulatory frameworks were suggested as possible solutions to the enumerated challenges.