Survival of bacteria in soil subsequent to greywater application

Greywater can carry many pathogenic bacteria. Survival of these bacteria in the soil‐greywater environment may pose a health risk associated with greywater reuse. This study investigates the survival of a biotracer bacterium (nalidixic acid‐resistant Escherichia coli ‐ E. coli NAR) in soil irrigated by greywater. Greywater volumes obtained from the showers, sinks, laundry and kitchens of five houses in Irbid, Jordan, were mixed with the biotracer and applied to four 1 m × 1 m plots. Tap water was applied to a fifth plot as a control. For 30 days, soil samples were collected from the five plots and then analysed to determine the biotracer content. The results showed that the biotracer survived for 15 days in the plot irrigated by kitchen greywater. The biotracer cells survived for 10, 10, 10, and 7 days in the other plots irrigated with tap water and greywater from showers, sinks, and laundry, respectively. The longer survival of the cells in the plot irrigated by kitchen greywater may be attributed to the higher BOD and nutrients in this greywater.