Reduced to a puddle of melted plastic. Longford fire, 2026
Most households rely on their water tank when a bushfire hits, whether it's for firefighting, topping up a pump, or just having water on hand once the power and mains supply go down.
The problem is that the common polyethylene tank, the black or green plastic tank you'll see on most rural properties, is itself vulnerable to the same fire you're facing.
Radiant heat alone, without direct flame contact, is enough to destroy a polyethylene tank. It has happened in actual fires, including at Wye River in 2016 and more recently at Longford and Natimuk in 2026. In each case the tank simply melted, taking out your water supply at exactly the moment you need it most.
Risks
Plastic tanks can melt during a bushfire
Plastic water tanks are common on rural properties, but they’re highly vulnerable to radiant heat and flame.
When exposed to bushfire conditions, they can fail catastrophically - losing stored water right when it’s needed most.
When fire approaches:
Radiant heat softens and tank walls melt
Flames melt plastic fittings and pipes
Water supply is lost for fire fighting and protection
Burning plastic spreads fire and toxic smoke
Polyethylene tanks can melt and collapse from radiant heat alone, even without direct flame contact
A tank sited close to a home can lose its water at the time your home needs it most
A collapsing tank near a structure adds its own fuel load right against the structure and the physical impact can be similar to driving a vehicle into the structure at 50km/hr
Combustible platforms, stands or edging under a tank, such as treated pine, can be enough fuel on their own to bring the tank down in a fairly modest ember attack
Fixes
Where you can site tanks away from the house, sheds and other structures, so a failing tank doesn't add fuel next to a structure
Use a non-combustible stand, platform or base for the tank rather than treated pine or other timber
Keep the area around the tank clear of vegetation, mulch and stored combustible items
Bury supply pipes well below the surface (at least 300mm cover).
A buried poly pipe can fail if nearby tree roots catch fire
Don't assume a water-filled poly pipe is safe, it can still fail under radiant heat even with water inside
Keep your tank full well before the fire season
If you're installing a new tank, ask about steel or concrete options for a more fire-resilient water supply
Locate two adjacent plastic 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
These small fixes genuinely help. What material your tank is made from, where it is sited and what you build it on are practical steps you can take to protect the water supply your family will be counting on.
A melted tank can leave your property without water and add fuel to the fire.
Quick fix: Clear vegetation and flammable materials around tanks. Keep the area free of leaf litter, grass, and debris.
Long‑term fix:
Install metal or concrete tanks where possible
If using plastic tanks, shield them with metal or masonry barriers or earth mounds
Fit metal pipes and valves instead of plastic
Position tanks away from buildings and vegetation
Provide easy access for fire fighting vehicles and pumps
These measures help ensure your water supply remains usable during a fire.
Why it matters
Your water tank is vital for fire fighting and property protection. Protecting it means preserving your most valuable resource when conditions turn extreme.
Take action today
Clear vegetation around tanks
Replace plastic fittings with metal ones
Add heat shields or barriers around tanks
Consider upgrading to metal or concrete tanks
Keep tanks accessible for fire fighting vehicles
For more on protecting your water supply and pump from bushfire, visit our Resource Hub.
