It tastes horrible but smoke-tainted rainwater is probably safe to drink, unless you're in an area directly affected by fire, Victoria's Department of Health and Human Services says.
Water is selling out in supermarkets across Victoria after rain contaminated by smoke fell across the east of the state this week.
"The Department is aware of queries from people living outside bushfire-affected areas reporting the drinking water from their rainwater tank tastes of smoke," a DHHS spokesperson said.
"The smoke taint alone is unlikely to be a health concern.
"However, if you are concerned about the taste of your rainwater, use bottled water for drinking and continue to use your rainwater for other uses."
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Water filtration provider, Puretec, said there was no one-size-fits-all approach and that water in each case should be tested by a certified laboratory before drinking, including arsenic and chromium levels.
"For sediment/ash removal, we suggest a 5 to 20-micron pleated sediment filter and for smoke smell/taste, we would recommend an activated carbon cartridge," Puretec spokesperson Georgia Bonham said.
"In most cases, there is also the possibility of bacteria like E.coli, so we would recommend ultraviolet sterilisation and sanitisation.
"We would also point out that filters may need to be changed more frequently, due to the higher than usual content of contaminants."
Ms Bonham said residents should seek advice before installing filtration systems to ensure they suited individual circumstances, including flow rates and the number of people using water.
Fireground water unsafe
Those affected directly by the fires were much more likely to have dangerously contaminated water.
"A bushfire affected area is where water retardant and water bombing activities have occurred, and ash has fallen directly onto the properties," the DHHS spokesperson said.
"If you live in a bushfire affected area, your private drinking water could be contaminated from debris, ash, dead animals, aerial fire retardants and water-bombing.
"If the water tastes, looks or smells unusual, do not drink, use for food preparation, brushing teeth or give to animals (pets or livestock).
"Boiling water doesn't remove fire retardants or other chemicals from your water.
"Fire-affected water in your tank can still be used for irrigation, toilet flushing and firefighting purposes. Water testing is not necessary."
The DHHS advice conflicts with the national Guidance on use of Rainwater Tanks report, which says most bushfire-affected water is likely to be safe.
"Bushfires generate large amounts of smoke, ash and debris that can settle on roof catchment areas," the report says.
"In addition, it is possible that fire retardants or foams may also be deposited on roofs.
"Such material can be washed into tanks, either when water is applied to the roof as part of fire protection activities, or when it rains after a bushfire.
"Although the presence of ash and debris in rainwater does not represent a health risk, it could affect colour, turbidity and taste.
"The recommended concentrations of the commonly used retardants and foams should not represent a health risk, but they may affect the taste of the water if washed into a rainwater tank."