Samples of borehole water were randomly collected from twenty households in the Lagos-Ogun axis of southwestern Nigeria. The samples were analyzed for silver, iron, manganese, lead, nickel, magnesium, cadmium, zinc, sodium, potassium, pH, turbidity, dissolved oxygen, electrical conductivity, alkalinity, total hardness, chloride, nitrate and sulphate following standard methods of water analysis. Results obtained were compared with global background values and WHO guidelines for drinking water. The pH values ranged from 4.17 ± 0.26 to 6.07 ± 0.27 while the metal pollution indexes are between 0.01 and 0.11. Cadmium, manganese, iron and nitrate (mg/L) levels were found to be relatively high in most of the water samples. Results obtained were analyzed statistically. Health risk assessment for exposure to cancer and non-cancer indices was evaluated. Kempster and co-workers classification of drinking water quality was applied; nineteen of the twenty household water samples were found to fall short of the ideal water quality suitable for lifetime use.

Contamination by heavy metals is a serious threat to aquatic systems due to their level of toxicity at elevated levels. The pollution of urban watersheds is of particular concern because of its potential impact on the watershed ecosystem and the receiving larger water bodies. This study assessed the occurrence and distribution of cadmium, copper, nickel, lead and zinc in water and sediment samples collected from three urban watersheds in Lagos, Nigeria. The concentrations of metals were determined using atomic absorption spectrometry. The health risk index (HRI) of water usage was evaluated for both adults and children. HRI for cadmium and lead in some of the watersheds recorded HRI > 1 values, a cause for health concern. The pH of water ranged from 6.48 ± 0.28-6.54 ± 0.47 (2016) and 6.18 ± 0.56-6.53 ± 0.17 (2018) respectively while, for sediments, the pH values ranged from 6.14 ± 0.48-6.9 ± 0.15 and 5.38 ± 0.22-6.4 ± 0.38 for 2016 and 2018 respectively. The levels of metals in the water samples during the 2016 sampling cycle were found to be within the World Health Organization (WHO) guideline limits for drinking water. However, the 2018 cadmium, lead and zinc concentrations for Ira-Ipaye and Akesan watersheds exceed the WHO guideline limits. Cadmium was not detected in Ira-Ipaye and Akesan 2016 sediment samples. Statistical t-test and analysis of variance (ANOVA) were used to ascertain significant differences of metals concentration in the three watersheds. The pH and metal concentration values obtained for water and sediment for the year 2016 and 2018 were non-significantly different.

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Introduction The inadequacy of pipe borne water supplies in urban centers is a growing problem. In recent years, packaged waters became major sources of drinking water in the households and at work. Aim This study aimed at evaluates the physical and chemical quality of packaged water sold in some part of Lagos Metropolis. Compare the quality with that of tap water; and check compliance with respect to national and international regulatory standards. Materials and Methods Thirty tap water and fifty seven packaged water samples of different types were selected by random sampling and analysed for trace metals using atomic absorption spectrometry; Total hardness was measured titrimetically; pH, electrical conductivity and anions were measured using meters. Results and Conclusion The results showed that the concentrations of trace metals and anions in both tap and packaged waters were below the drinking water threshold values stipulated by national and international agencies, with the exception of the nitrate (NO3-), where 11 % and 20 % respectively of the bottled and sachet water samples investigated exceeded the USEPA standard of 10 mg L-1. This finding may result from the geological formations through which the ground water flows and substances dissolving from either natural sources or from household plumbing systems. This study concludes that the systematic monitoring by drinking water authorities of water quality is essential and the enforcement agencies in the state (NAFDAC and the Ministry of Health) need to get the producers of 'packaged water' to comply with the national drinking water guidelines.