Assessing environmental risks of laundry detergents in greywater used for irrigation

The objective of this study was to assess the environmental risk posed to Australian and New Zealand ecosystems by the presence of powdered laundry detergents in greywater used for irrigating gardens. Fifty powdered laundry detergents were assessed and all contained hazards which posed moderate to very high risks from increased alkalinity, sodicity and salinity to plants and soils when used at manufacturer-recommended doses and the resulting greywater used for irrigation. A number of detergents had phosphorus and boron concentrations considered to be a high risk for a number of plants. Risk to groundwater quality was also evaluated and found to potentially be a tighter constraint than risk to plants and soil where irrigation reuse is extensive in arid areas. A detergent environmental performance index was composed on risks assessed for three scenarios to compare with a washability performance index for the same powders. Only one detergent exceeded the 80% environmental index (100% = low risk from all hazards assessed) and maintained wash performance above 85%. The analysis suggests that for poorly drained soils greywater reuse is not recommended for most of the powdered laundry detergents evaluated. However the methodology may provide a basis for environmental labelling of detergents.