Choosing the right diesel storage solution can significantly impact cost, safety, compliance, and on-site efficiency.

Whether you're managing a fleet, operating machinery on a worksite, or storing fuel for agricultural use, the decision between self-bunded diesel tanks and poly diesel tanks is one of the biggest purchasing choices you’ll make. Both offer reliable storage, but each suits different environments, budgets, and compliance needs.

This guide breaks down the differences, benefits, and ideal applications so you can choose the tank that fits your operation with confidence.

What Is a Self-Bunded Tank?

A self-bunded tank (also known as a double-walled or dual-skin tank) is constructed with an inner tank that holds fuel, and an outer tank that forms the protective bund.
The gap between the walls safely captures leaks, spills and overfills — providing built-in secondary containment.

Key features:

• Steel construction for high durability
• Integrated spill containment (110% capacity)
• Suitable for diesel, lubricants, waste oil and some chemicals
• Complies with strict fuel storage standards
• Long operational lifespan

Self-bunded tanks are typically available from 500L to 150,000L+ and are widely used in industrial, commercial and agricultural settings.

What Is a Poly Diesel Tank?

Poly diesel tanks are made from heavy-duty polyethylene and designed specifically for portable or ute-mounted fuel transport.
They are lightweight, corrosion-resistant and ideal for mobile refuelling.

Key features:

• UV-stabilised polyethylene
• Lightweight and easy to transport
• Impact-resistant and rust-proof
• Available in many on-the-go sizes (50L–10,000L)
• Commonly used on farms, job sites and with service vehicles

Unlike self-bunded tanks, poly tanks typically do not provide inbuilt secondary containment.

Self-Bunded Tanks vs Poly Diesel Tanks: Feature Breakdown

1. Portability

Poly Tanks:
Best for mobility. Easy to transport on utes, trailers or machinery. Ideal for mobile refuelling.

Self-Bunded Tanks:
Heavy, fixed in place or moved via forklift or crane. Ideal for permanent or semi-permanent installations.

Winner: Poly diesel tanks for portability.

2. Durability & Lifespan

Self-Bunded Tanks:
Made from steel, engineered for long-term use and harsh conditions. Lifespan often 20+ years.

Poly Tanks:
Durable but less resistant to extreme heat, UV exposure over long periods, or high-volume commercial use.

Winner: Self-bunded tanks for long-term durability.

3. Compliance & Safety

Self-Bunded Tanks:
Meet strict Australian fuel storage regulations. Built-in bunding equals compliant spill protection.

Poly Tanks:
Compliant for transport, but not suitable as a fixed storage solution where secondary containment is required.

Winner: Self-bunded tanks for compliance and safety.

4. Capacity Options

Self-Bunded Tanks:
Suitable for bulk storage — thousands to tens of thousands of litres.

Poly Tanks:
Typically lower capacity — most commonly 200L to 10,000L.

Winner: Self-bunded tanks for capacity.

5. Cost

Poly Tanks:
More affordable upfront. Best for smaller operators or those not requiring permanent storage.

Self-Bunded Tanks:
Higher initial cost but greater lifespan, security and compliance… often better long-term ROI.

Winner: Poly tanks for upfront cost, self-bunded tanks for long-term value.

6. Fuel Security & Theft Prevention

Self-Bunded Tanks:
Can include lockable pump bays, anti-siphon protection, monitored access and fuel management systems.

Poly Tanks:
Can be lockable, but are more exposed and easier to access.

Winner: Self-bunded tanks for fuel security.

Which Tank Should You Choose?

Choose a Self-Bunded Tank if you need:

Bulk fuel storage

• Maximum safety and compliance
• Minimal environmental risk
• Long-term onsite storage
• Pump bay integration, monitoring, or automated fuel systems
• Theft and tampering protection

Perfect for:

• Civil & construction
• Mining
• Transport fleets
• Industrial sites
• Large farms

Choose a Poly Diesel Tank if you need:

• Mobile refuelling
• Lightweight equipment
• Low-cost transport solutions
• A tank that can be moved daily or weekly
• Ute-mount or trailer-mount flexibility

Perfect for:

• Agriculture
• Service vehicles
• Contractors
• Small to medium worksites

Can You Use Both?

Yes — many operators run both systems:

• A large self-bunded tank for bulk storage
• Smaller poly diesel tanks on vehicles for daily refuelling
• This setup reduces downtime, lowers costs, and keeps equipment moving without constant fuel deliveries.

If your goal is long-term, compliant, high-volume storage, choose a self-bunded diesel tank.
If you need flexibility and on-the-go refuelling, a poly diesel tank is the smarter investment.

Optimising your fuel storage setup will improve efficiency, reduce costs, improve safety, and extend equipment lifespan.