Addressing The Risk Of Polluted Irrigation Water

A recent study published by the Water Research Commission highlights the urgent need for identifying on-farm treatment options to help reduce the high levels of microbial contamination in irrigation waters, thereby reducing the associated food safety hazards for consumers. Denene Erasmus summarises some of the report’s key findings.

- Denene Erasmus

Many of South African rivers from which water is drawn for agricultural irrigation purposes are carrying extraordinarily high pathogenic loads. Produce irrigated using this water are often minimally processed fresh fruit and vegetables or products that are eaten raw.

The risks of using this water to produce edible crops have been weighed against the backlog of providing sanitation services and food insecurity by various local research organisations, including the South African Water Research Commission (WRC). The WRC, in co-operation with the Department of Agriculture, Forestry and Fisheries (DAFF), published a report titled, ‘Scoping study on different on-farm treatment options to reduce the high microbial contaminant loads of irrigation water to reduce the related food safety risk’. According to the report, in addition to the threat to consumer health, large-scale outbreaks of food-borne illnesses will affect sales and damage consumer confidence in local produce. Such outbreaks could also result in legal challenges that could potentially prevent entry into lucrative export markets, as well as produce possibly being rejected by local consumers. “The consequences would be disastrous for SA agriculture considering that this sector is one of the largest employers of labour in the country and rapidly increasing in economic importance,” the report reads.

CAUSES OF RIVER POLLUTION

According to the study, insufficient sanitation facilities and inadequate sewage treatment works throughout South Africa are considered the primary sources of pollution. Sanitation facilities in rural areas, in particular, are often inadequate for the size of the populations residing in those areas. “Consequently, rivers have become receivers of waste and waste water while still being used for agricultural irrigation,” says the report.