Groundwater bacteriological quality assessment: impact of urbanization and agricultural activity

Groundwater from boreholes is the major source of bottled water in Algeria. The aim of this study is to determine the bacteriological quality of groundwater that serves bottled water production. A total of 73 groundwater boreholes were sampled and analyzed for the required bacteriological parameters. The analysis was performed in accordance to ISO standards methods. There should be no bacteria growth for each bacteriological parameter to qualify the groundwater of good bacteriological quality. The bacteriological analysis highlighted that 37 of the 73 groundwater samples (51%) were of poor bacteriological quality while 36 of them (49%) were of good bacteriological quality. Total coliforms and E. coli were the major sources of contamination with respectively 35 and 24 contaminated samples, followed in order by Pseudomonas aeruginosa, enterococci and sulfite reducing anaerobic bacteria spores with respectively 8, 7 and 2 contaminated samples. Bacteriological quality was strongly and negatively correlated with urbanization and/or agricultural activity parameter (r = −0.454). The performed logistic regression model showed that the presence of urbanization or agricultural activity multiplies significantly (P < 0.001) the risk by 7 of being a poor bacteriological quality groundwater. These findings are useful to avoid drill costs and to take the best strategy to protect groundwaters. HIGHLIGHTS Half of groundwaters do not satisfy the bacteriological quality criteria.; Total coliforms and E. coli are the major sources of contamination in the studied groundwaters.; The presence of urbanization or agricultural activity has a negative impact on groundwater bacteriological quality.; Evidence was shown that drilling costs could be avoided by adopting the groundwater quality prediction tools.