Enterococci and E. coli levels are two measures used to determine if waterways are safe for swimming. What are these and why measure them?
What are they?
Enterococci and E. coli are two strains of bacteria that live in the gut of warm-blooded animals. They are considered Faecal Indicator Bacteria because high numbers of them in water can mean the presence of faecal matter from animals (including humans, dogs, birds). They are introduced to waterways through animal and bird droppings, effluent and waste water discharges, and stormwater run-off.
Why test for them?
We worry about these two types of bacteria because their presence in high numbers can make you quite sick;
Enterococci: Can cause urinary tract infections, bacteremia, and endocarditis
E.coli can cause diarrhoea, abdominal pain and fever.
Not only that but finding these bacteria in large quantities suggests that there could be sewage in the water which can carry all sorts of other other pathogens that we don’t test for such as salmonella, campylobacter and giardia.
What's a safe amount?
Enterococci levels above 280 per 100 mL and E. coli above 540 per 100 mL (in two consecutive samples within 24 hours) mean that the water poses an unacceptable health risk from swimming.
How’s Te Wai o Pareira doing?
Rivercare has established testing of Te Wai o Pareira at two sites, Taipari Strand and Chapman Strand. Unfortunately we often see high levels of Enterococci at both sites, especially after rainfall but sometimes even in dry weather if there is a sewage overflow. Our testing and advocacy was instrumental in getting Te Wai o Pareira onto the Safeswim database so the public can check before entering the water.
What can you do?
Report overflows, smells, and leaks to Watercare—these contribute to high bacteria levels. Contacts are either (09) 442 2222 and press 1 or report online via the Watercare website
Check swim safe before taking a dip, especially after heavy rain.
Don't flush items like wet wipes—this helps prevent overflows and contamination.
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