Rainwater tanks and mosquitoes, are we missing something?

Dengue fever is a serious health issue. Rainwater Harvesting Australia supports a regular inspection and maintenance program for all rainwater tanks including mosquito control and this is already well established. The proposition that rainwater tanks currently represent a serious risk of a Dengue fever outbreak for Brisbane Residents is not supported by the science presented or an informed commentary from a range of health and rainwater harvesting experts.

Mosquitoes prefer water that is stagnant, warm, shallow, open to the environment and contains high levels of nutrients. Simply put, because of these key parameters, mosquitoes would prefer puddles, pot plants and wetlands to rainwater tanks.

So, an operating rainwater tank is unlikely to aid mosquitoes. Moreover, the mosquito vector of Dengue Fever has a very low range of less than 200 metres and, it is therefore, almost impossible for rainwater tanks to foster any “outbreaks”.

The Rainwater Harvesting Industry specifies mosquito control and supports a program of inspection and maintenance of all rainwater harvesting system elements. This is all clearly documented in the Rainwater Harvesting Residential Design Specification produced by Urban Water Cycle Solutions and Rainwater Harvesting Australia¹ and the Queensland Development Code (MP 4.2 and MP 4.3).

The CSIRO has not presented evidence that the current, well established regulatory controls over rainwater tanks have failed or are not well understood and therefore pose a significant risk to public health.

International literature on Dengue disease control states:

There is a great variety of man-made containers on backyards or patios that collect rain water or that are filled with water by people where dengue vectors thrive. Disposing of unused containers, placing useful containers under a roof or protected with tight covers, and frequently changing the water of animal drinking pans and flower pots will greatly reduce the risk of dengue infections. Water storage containers should be kept clean and sealed so mosquitoes cannot use them as aquatic habitats.²

Queensland Health are not referenced in the ABC health article, but they have established documentation about mosquito prevention around the home. There are a wide range of potential places for mosquitoes to breed in residential areas³. The report referenced by the ABC unfortunately focuses on one that is likely the lowest risk!

Rainwater Harvesting Australia and the Queensland Development Controls clearly require that a stainless steel mesh with less than 1mm aperture is built into the specification for tank inlets, rainhead leaf diverters and tank outlets.

Rainwater Harvesting Australia supports the 2 million plus households in Australia who rely on rainwater for drinking water, as well as the further 3 million plus households using rainwater to supplement mains water supplies. There are no reported widespread health impacts from using or drinking rainwater.

The last case of dengue fever in Brisbane was in 1948. Scaremongering and poorly researched news stories about health risks need to be called to account.

¹ http://rainwaterharvesting.org.au/wp-content/uploads/2018/01/Rainwater-Harvesting-Guide-Approved.pdf
² https://www.cdc.gov/dengue/entomologyecology/m_habitats.html
³ https://www.qld.gov.au/health/conditions/all/prevention/mosquito-borne/control/breeding-sites

Source: Media Release by Rainwater Harvesting Australia