Sampling of E.coli levels in sea produces ‘erratic’ readings: WaterCan
A water quality expert says tests for E.coli levels in the sea can produce extremely erratic readings.
Last week, Durban University of Technology’s Institute for Water and Wastewater Technology flagged high levels of E.coli at 11 of the city's beaches, including Addington, Country Club, Umdloti, and Virginia.
But eThekwini Municipality countered that its samples returned acceptable levels of the bacteria and insisted that the beaches were safe for swimming.
"The sea is a very finicky place to be doing E.coli tests,” said Jonathan Erasmus, the KZN Project Manager for WaterCan,
“If there is a huge amount of movement, you have currents continuously changing, and all these things have to be taken into effect. It is good to be testing it.
READ: E.coli risks can no longer be ignored, warns ActionSA
“I am not saying you must not test it. If you get a week of easterly swells the bay will have spikes the whole time. In winter, you may see a southerly swell it is crystal clear, and you can see fish.”
Erasmus believes it might depend on when the tests were taken.
"When DUT did its testing, there was an easterly swell the day they did the test. What generally happens on the easterly swell is you have to then factor in the Umgeni River, which is the main polluter. Every now and again, you have an easterly swell, and you can imagine that waste has come out of the river, and instead of being pushed north, it is pushed towards the coast, and the city did its testing two days later. They went down to the southerly swell, of course, and they said the sea is fine."
Erasmus said we must not lose sight of dealing with the root of the pollution.
"All we are doing now is testing the final destination. We know it is there. We know the northern wastewater treatment works are broken. We know for a fact that at least 20 million litres of raw sewage every day enters the system there."
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