Stinkwater groundwater not fit for human consumption – CSIR

Groundwater in Stinkwater, north of Pretoria, is not safe for human consumption and even contains faecal pollution, a Council for Scientific and Industrial Research (CSIR) study has found.

The results of the study, published on Thursday, were part of a three-year research project aimed at investigating the health risks that untreated groundwater posed to residents and exploring potential interventions.

“People need clean water to consume, irrigate, for livestock, etc, but water is a luxury many do not have access to,” said CSIR senior scientist and laboratory manager Wouter le Roux.

Le Roux said Stinkwater residents had no access to piped water distributions and relied on water which municipal trucks delivered. But he added that it wasn’t always enough.

Le Roux explained that residents had found their own solution to water access through hand-dug wells.

This untreated water exposed them to various health risks.

According to a CSIR statement, 144 water samples were collected over a two-year period over the wet and dry seasons. Most samples were taken from hand-dug wells.

“The study found that fluoride exceeded the drinking water standard ( a maximum of 3.6 mg/L) in 9% of samples and nitrate exceeded the drinking water standard (an average of 23.1 mg/L) in 87% of samples.

Escherichia coli bacteria, which is used as an indicator of faecal pollution, was also detected in most samples, Le Roux said.

“Nitrate can occur naturally in surface and groundwater at a level that does not generally cause health problems. Groundwater can be contaminated with nitrate that comes from fertilisers, septic systems, animal feedlots, industrial waste and food processing waste.”

He added that the South African National Standard specifies that drinking water should not contain more than 11 mg/L nitrate (measured as N03-N) but in this study, the average nitrate concentration was found to be 23.1 mg/L.

“Most researchers agree that water containing nitrate at concentrations that is above the 10 mg/L safe level is not safe for human consumption because there is a risk of adverse health effects like methaemoglobinaemia. Drinking water should also not contain any E. coli bacteria as this suggests that there is a risk of diarrheal diseases.”

Le Roux said the CSIR was looking at ways to use nano-engineered clays and plants to remove nitrate from the water, rendering it safer for consumption.

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