 According to a study by the International Water Management Institute (IWMI), these risks need to be carefully considered, but the importance of this practice for the livelihoods of countless smallholders must also be taken into account.Studies on soils irrigated with untreated wastewater for 50 years show an accumulation of heavy metals in the soil, but also that they accumulated in plants to a lower extent.Another study found bacterial contamination of canal water used for bathing and of groundwater used for drinking water supply in the irrigated areas where wastewater was being reused, resulting in a high incidence of diarrhea and skin irritations.