NSW Health advice to keep rainwater tanks safe for drinking

PREVENTION is better than cure, and when it comes to rainwater, giving your tanks and guttering a health check can help you to avoid all sorts of nasties.

A spokesperson from NSW Health said that while the community can remain assured that well maintained rainwater tanks provide good quality drinking water, simple maintenance and care is important.  

Rainwater collected and stored in domestic tanks will contain a range of microorganisms from one or more sources. While most organisms will be harmless, there are some to watch out for. 

“The biggest health risk from rainwater is bacterial contamination from birds and other small animals,” a NSW Health spokesperson said. “However, leaves and dust from gutters and roof catchments may wash into the tank leading to taste and odour problems.”

NSW Health recommend households follow these simple steps to avoid problems.

  • Regularly clean gutters, roofs and prune overhanging trees.
  • Seal and fit fine screens on all inlets and overflows to stop light, prevent vermin, leaf litter and dirt, and mosquitoes from breeding
  • Use a first flush diverter.
  • Remove or paint over sources of lead on the roof, like flashing, screws or solder.
  • Have your tanks desludged every two to three years to prevent silt build up.
  • Fush taps for two to three minutes before drinking or cooking at the start of each day to clear rainwater that has been standing in pipes.

Spray drift in agricultural areas often raises concerns of potential contamination of roofs used as catchments for rainwater.

If an area is over sprayed, NSW Health recommend disconnecting the rainwater system to prevent chemicals entering the tank, then clean the roof or wait until after the next rainfall to reconnect.


Rainwater tanks can provide excellent habitats for mosquito breeding. In addition to causing nuisance, certain types of mosquito can be vectors for diseases such as dengue, Ross River and Barmah Forest viruses. 

“Insect screens are the best way to keep a tank free of mosquitoes,” a spokesperson from NSW Health said.  “NSW Health also urges people to be aware kerosene is no longer recommended to prevent mosquitos breeding in tanks. The Australian Drinking Water Guidelines now recommend the use of the pesticide s-methoprene to control mosquito larvae.”


It isn’t only rural areas that need to be careful: urban areas can also be at risk of contamination from heavy traffic and industry. NSW Health recommend in these situations using the public water supply for drinking and cooking.


NSW Health also warns of another water related pathogen, amoebic meningitis. In recent years, a tragic outcome of exposure to the pathogen was the death of a number of children.

“NSW Health advises in the summer months that the potentially fatal amoebic meningitis (Naegleria fowleri) can present a risk to people swimming in unchlorinated water, or those playing under sprinklers and hoses,” a NSW Health spokesperson said. 

“The amoeba lives in warmer conditions in freshwater and soil and water sources that seasonally exceeds 30 degrees Celsius or continually exceeds 25 degrees Celsius may be a risk. Although chances of infection are extremely rare, cases of Naegleria meningoencephalitis have been recorded in South Australia, Western Australia, Queensland and New South Wales in untreated water supplies such as bore water and a farm dam.