Sachet water (SW) is a major source of drinking in most Nigerian homes, thus making it a possible conveyance medium for health risks due to contamination if persist rather than for replenishment of the body. This study collected SW from three busy neighborhoods in South-West Nigeria and investigated for the presence of indicator bacteria (Escherichia coli (E. coli), Total Coliform (TC), Total Heterophilic Bacteria (THB), Staphylococcus (Staph)) and some physio-chemical parameters (total dissolved solids (TDS), pH, electrical conductivity (EC), and salinity). Multi-variable and exploratory statistical methods were applied to the results to determine correlations between bacterial contamination levels and perceived brand reputation. Bacteriological tests with raw SW samples appeared too numerous to count (TNC) and thus required serial dilutions. After seven-fold serial dilutions, results obtained revealed that SW brands with good reputations had no TC and E. coli and was statistically significant with groupings of other SW brands (χ² = 12.28; p < 0.05 and χ² = 37.96; p < 0.05). Additionally, SW brands with poor reputations had mean values of TC ($19.7\times {10}^8 \mathrm{cfu}/\mathrm{mL}$; $14\times {10}^8 \mathrm{cfu}/\mathrm{mL} 1.15\times {10}^8 \mathrm{cfu}/\mathrm{mL}$) and E. coli ($18.2\times {10}^8 \mathrm{cfu}/\mathrm{mL}$; $38.7\times {10}^8 \mathrm{cfu}/\mathrm{mL},32.4\times {10}^8 \mathrm{cfu}/\mathrm{mL}$) exceeding the threshold value of zero set by the World Health Organization (WHO). Only one sample from a poor reputation brand tested positive for Staphylococcus and was not statistically significant (χ² = 5.2191; p = 0.074). Principal Component Analysis (PCA)/Factor Analysis (FA) revealed that most of the SW had fecal contamination was the major source. Therefore, this study suggests that periodic cleaning of distribution lines, location-specific treatment, and other quality control (QC) measures should be enforced to reduce water security risk for SW consumption in the region.

Biochar has proven effective in the remediation of excess nitrogen from soil and water. Excess nitrogen from agricultural fields ends up in aquatic systems and leads to reduced water quality and the proliferation of invasive species. This study aimed to assess the efficiency of chemically surface-modified biochar produced from invasive Pistia stratiotes L. for the adsorption of inorganic nitrogen (NH₄⁺ and NO₃⁻). Biochar structure was investigated using scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and inductively coupled plasma mass spectrometry. The results from adsorption experiments indicate that NH₄⁺ removal was optimal (0.8–1.3 mg N g⁻¹) at near-neutral pH levels (6.0–7.5), while NO₃⁻ removal was optimal (0.4–0.8 mg N g⁻¹) under acidic pH conditions (4.8–6.5) using the modified biochar. These findings highlight the significance of solution pH, biochar morphology, and surface chemistry in influencing the adsorption of NH₄⁺ and NO₃⁻. However, further studies are necessary to assess the potential oxidative transformation of NH₄⁺ to NO₃⁻ by biochar, which might have contributed to the reduction in NH₄⁺ in the aqueous phase.

Land Use and Land Cover (LULC) properties give vital information about pollution signatures in rivers, and they help develop best management practices (BMPs) for effective water resource management. This work employs multivariate statistical methods, receptor modeling, connectivity analysis, and univariate trend analysis to investigate pollution sources across spatiotemporal scales in the Manawatu River, New Zealand. A positive matrix factorization (PMF) method was applied to interpret possible contamination sources. A 25-year dataset (1989–2014) comprising 12 water quality variables from three sites was used. Runoff connectivity analyses identified high-producing grassland (HG) as the most dominant pollution class in all sub-catchments. Univariate analyses revealed that nutrients and sediments were higher than in the initial monitoring years. The PMF analysis found possible pollutants causing impairment, which required attention from waste managers. PMF also showed that point, natural, and agricultural sources significantly contributed to pollution downstream of the river. In the midstream, the erosion, point, and agricultural sources were significant contributing factors. Agricultural pollution and soil erosion were the main contributors to the upstream sub-catchment area. This study suggests that BMPs with a high retention capacity are needed in specific locations in the catchment area to filter high concentrations of pollutants generated.

This study was conducted in Ekpoma, a town dependent on rainwater and river water from nearby areas because of a lack of groundwater sources, and the physicochemical and bacteriological (heterotrophic plate count [HPC], total coliform count [TCC], and fecal coliform count [FCC]) properties of 123 stored river water samples grouped into five collection districts (EK1 to EK5). The results were compared with regulatory standards and previous regional studies to identify water quality trends. While most physicochemical properties met drinking water standards, 74% of samples had pH values > 8.5. Twenty-seven samples were fit for drinking, with EK4 having the highest number of bacterio-logically unsuitable samples. Ten bacterial species were identified, with Gram-negative short-rod species such as Escherichia coli, Klebsiella pneumoniae, and Salmonella typhimurium being predominant. HPC values varied from 367 × 10⁴ to 1320 × 10⁴ CFU/mL, with EK2 (2505 × 10⁴ CFU/mL) and EK5 (1320 × 10⁴ CFU/mL) showing particularly high counts. The TCC values ranged from 1049 × 10⁴ to 4400 × 10⁴ CFU/mL, and the FCC values from 130 × 10⁴ to 800 × 10⁴ CFU/mL, all exceeding WHO limits (1.0 × 10² CFU/mL). Historical data show no improvement in water quality, emphasizing the need for individuals to treat water properly before consumption. The findings provide baseline data for local water authorities and serve as a wake-up call for adequate water treatment, storage interventions, and community education on water security. Additionally, this study offers a practical process for improving the quality of water stored in similar regions.