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2 May 2019 2 min read

water tank in garden
©  (C) Ari Hatzis

Rainwater tanks are a great alternative water supply and can help save you some cash, especially during times of water restrictions. But they can also become breeding grounds for mozzies that can carry all sorts of nasty infectious diseases, including dengue fever.

The Aedes aegypti mosquito infects hundreds of millions of people across the globe each year with dengue, Zika, chikungunya and yellow fever.

You might think of these as being diseases confined to the tropics. But new research has found the mosquito in a number of towns in the Wide Bay region, closer to Brisbane.

An aedes aegypti mosquito. Image: Muhammad Mahdi Karim

Our vector ecologist Dr Brendan Trewin was one of the lead researchers on this study. Brendan studies insects that transmit pathogens and their contact with humans so we can better understand how diseases spread.

“Previous studies had suggested that conditions in Brisbane were inhospitable for the species during winter, but our findings show that rainwater tanks could provide year-long protection for the Aedes aegypti mosquito in Brisbane and other sub-tropical areas of Australia,” Brendan said.

It is believed that more than 40 per cent of Brisbane properties now have rainwater tanks, though this number could be much higher as there is no formal registration or monitoring procedure.

“The last time Brisbane had significant Aedes aegypti and dengue epidemics they also had a lot of unsealed rainwater tanks, and our research suggests it was the decision to remove these tanks in the 1950s that was one of the keys to driving the disease-carrying mosquito out of the city,” Brendan said.

Our researchers measured mosquito survival and development during simulated Brisbane winter conditions in rainwater tanks and buckets and found that 70 per cent of mosquito larvae survived to adult hood in water tanks, and 50 per cent in buckets.

Now, we’re not suggesting you should ditch your rainwater tank, but it’s important to be aware that if your rainwater tanks are not maintained properly, they could become a breeding ground for mozzies bringing with them potentially serious implications for Australian public health. And you might be unknowingly adding to the risk if you make modifications to your tank like removing the sieve that collects leaves from the roof and gutters, or adding modified downpipes.

As Australia's national science agency, we’re working on a range of tools to help safeguard Australia, from real time alert systems; quicker and smarter diagnostic tools; right through to sterilisation technology that eradicates the mosquito.

So what can you do to mosquito proof your tank?

  • Check there are sieves at the entrance and overflow and there are no gaps
  • Check for cracks in plastic tanks
  • Make sure the sieves aren’t rusting and there are no holes
  • Mosquitos feed on broken down leaves so keep gutters leaf free
  • Check that first flush devices are draining

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