RESEARCH FINDS RAINWATER UNFIT FOR HUMAN CONSUMPTION

A study by iYunivesithi Walter Sisulu researcher, Thokozani Mangesi, discovered harvested rainwater recorded higher levels of Escherichia coli (E. coli), a type of bacteria that can cause acute kidney failure due to faecal contamination.

Mangesi’s research explored and questioned the safety of rainwater collected by rural households for drinking in the O.R Tambo District, following its journey from the atmosphere, across different roof surfaces and into household storage containers.

Her study found that all the rainwater harvesting subtypes assessed were unfit for human consumption when compared with South Africa’s drinking water standards.

“Open drums concentrate microbes and minerals whereas sealed tanks accumulate the manganese,” she said.

Mangesi, also found high levels of Manganese, which when consumed in high concentrations over the years transforms into a dangerous neurotoxin causing a condition called Manganism, which damages the brain and leads to physical and mental changes.

Mangesi tested the water against official South African National Standard (SANS) drinking water standards, SANS 241, to determine whether it was suitable for human consumption.

The study found that tiled roofs were associated with bacterial contamination because their surfaces can trap dirt and bird droppings, while non-coated metal roofs can contribute to increased levels of zinc and other dissolved substances.

Her study compared tiled, coated steel and non-coated steel roofs and found that 11 of the 22 water quality parameters tested and showed significant differences between the roof types.

“I examined two household storage methods: open polyethylene drums and sealed polyethylene tanks. Six of the 22 parameters showed significant contamination differences between the two storage types, including E. coli, sulphate, calcium, iron, zinc and manganese,” Mangesi said.

“The infrastructural composition, that is the material of the roofs as well as the materials of the storages, determines much of the water quality that is found in rainwater harvesting,” said Mangesi.

She added that the results showed that changing one type of roof material does not necessarily remove all water quality risks.

“The roof types have a significant impact on the quality of water,” she said.

Mangesi also found that contamination can occur before rainwater reaches a household roof. And that lead was detected in atmospheric water samples, indicating that rainwater can be affected by pollutants in the atmosphere.

She said this challenges the common perception that rainwater is automatically clean because it comes from the sky.

“The water does not fall from the atmosphere as clean as we think it is because there are some other aspects in the atmosphere that are influencing the quality of the water,” she said.

Mangesi recommends the use of coated metallic catchments, first-flush devices that divert the initial water collected from the roof, or boil water before drinking.

Mangesi presented the study at the Annual Young Scientist Conference (AYSC), held at iYunivesithi Walter Sisulu’s Mthatha campus recently.

By Amahle Haseni