Reduced to a puddle of melted plastic. Longford fire, 2026
Know The Risk
Most households rely on their water tank when a bushfire hits, whether it's for firefighting knapsacks, supplying a fire pump, or just having water on hand after the power and water mains supply go down.
The problem is that the common black, cream or green poly (polyethylene) tank you'll see on rural properties is itself vulnerable to the same fire you're facing.me fire you're facing.
Radiant heat alone, without direct flame contact, is enough to destroy a poly tank. This happened at Wye River in 2016 and more recently at Longford and Natimuk in 2026. In each case tanks ruptured, taking out the water supply at exactly the moment it was needed most.
About poly tanks and pipes:
Are common on rural properties, but they’re highly vulnerable to radiant heat and flame
Can melt then rupture during a bushfire
The failed tank adds fuel to the fire
When exposed to bushfire conditions, they can fail catastrophically. When a fire approaches:
Radiant heat, without flame contact, softens tank walls leading to rupture
Flames melt plastic fittings and pipes
Water supply is lost for fire fighting and protection
Burning plastic spreads toxic smoke
The catastrophic failure of a tank sited against a structure can be similar to driving a vehicle into the structure at 50km/hr when it ruptures
Treated pine edging around a tank provides enough fuel to cause tank failure during a fairly modest ember attack it most
A buried poly pipe can fail if nearby tree roots catch fire and burn down to the poly pipe
Don't assume a water-filled poly pipe is safe, it can still fail under radiant heat even with water inside
Do The Fix
Good:
Position tanks away from a house, shed and other structures, so a failed tank doesn't add fuel to the fire
Keep the area around the tank clear of vegetation, leaf litter, grass, mulch, debris and stored combustible items
Use a non-combustible stand or platform
Avoid using a perimeter base made from treated pine or other timber
Bury supply pipes well below the surface (at least 300mm cover) and avoid having them pass near old tree roots
Fill your tank full well before the fire season
Locate two adjacent poly tanks a minimum of 2 metres apart to avoid the “chimney effect”
Avoid having a pump or control equipment in a combustible enclosure between adjacent tanks
Avoid storing combustible materials between or adjacent to poly tanks
Better:
Shield poly tanks with a metal or masonry barrier or earth mounds
Provide easy access for fire fighting vehicles
Provide a valve and a fitting that suits fire agency hoses
Install direction signs to identify the location of your tanks so they can be quickly located by a fire agency crew
Best:
Install metal or concrete tanks
Fit metal pipes and valves instead of plastic
For more on protecting your water supply and pump from bushfire, visit our Resource Hub.
