Abstract:
ABSTRACT
Achieving SDG 6 requires practical, low-cost monitoring frameworks that can be deployed where
laboratory capacity and budgets are constrained. This forms the basis for conducting a cross-sectional
survey of wells (n=9), boreholes (n=3), and rivers (n=2) across Ijebu Metropolis, Ogun State, Nigeria.
Field DO and laboratory BOD and COD were measured using standard procedures. Group differences
among water types were tested with the Kruskal–Walli’s test and examined BOD/COD as a
biodegradability index and mapped sampling points. Mean (range) values were DO 5.04 (3.70–6.30)
mg L⁻¹, BOD 1.78 (1.10–3.00) mg L⁻¹, and COD 4.63 (2.00–7.80) mg L⁻¹. BOD/COD averaged 0.43,
indicating a mix of biodegradable and more refractory organics. Kruskal–Wallis tests showed no
significant differences among water types. A few wells exhibited elevated COD with modest BOD,
consistent with less-biodegradable inputs. Organic matter levels were generally modest but
heterogeneous at the neighbourhood scale. By employing low-cost panel of DO, BOD, and COD, this
study provides actionable evidence for improving water quality in Nigerian cities. The use of simple
statistics and mapping directly supports the monitoring of SDG 6.1 (safe drinking water) and SDG 6.3
(water quality/wastewater), aiding in source protection, basic treatment, and community risk
communication.
