Poly vs. Steel Water Tanks: The Ultimate Guide to Choosing the Best Solution for Your Site

Choosing between a poly (polyethylene) tank and a steel liner tank is an important decision to make - whether its for your home, property, business or farm. Both options are icons of the Australian landscape, and while both store water effectively, they are designed for different settings, depending on your circumstances.

In this guide, we dive deep into the pros, cons, and best-use cases for each tank material to guide you to the best tank for your site.

Poly Water Tanks: The Versatile, Corrosion-Free Choice

Polyethylene tanks have become the go-to for modern Australian households and smaller rural setups. Made from high-quality, food-grade poly, these tanks are built to last in some of the world's harshest conditions.

The Pros:

• Corrosion and Rust Resistance: Unlike traditional steel, poly material does not rust or corrode. This makes poly tanks the ultimate choice for coastal properties where salt spray can corrode steel in a matter of years.
• Seamless Strength: Bushmans poly tanks, one of our preferred suppliers, manufacture their tanks in one piece using a rotational moulding process. This means there are no side seams or joints, which removes the most common "weak points" where leaks could start.
• UV Protection with Sunsmart® Technology: One common myth is that poly "plastic tanks" melt or become brittle in the sun. Bushmans uses Sunsmart® technology, incorporating UV stabilisers that prevent the sun’s rays from breaking down the material, ensuring a long service life even in the outback.
• Easy to Handle: Poly tanks are significantly lighter than a steel or concrete tank. This means delivery is much more straightforward, and they can be positioned easily on-site without needing a heavy crane or other forms of machinery.
• BPA-Free & Potable: All Bushmans poly tanks are food-grade and certified for drinking water storage, ensuring your family’s water remains safe and clean. While certified, Bushmans still highly recommends using a filter if you intend to drink the water from your rainwater tank.

The Cons:

• Size Limits: The largest capacity Bushmans offers is 46,400L, or 47,300L (Bushmans OzPoly North Queensland). If you need to store hundreds of litres for a large farm or commercial site as an example, you may require several poly tanks connected together rather than just one tank.
• Fire Susceptibility: While they are hard to ignite, poly tanks are more susceptible to heat damage during an intense bushfire if they are not shielded, or full of water.

Best For: Residential homes: Perfect for capturing rainwater for gardens or toilet flushing Townhouses & urban blocks: Using slimline models to fit into narrow side-passges Coastal properties: Properties on or around beaches Small businesses: Providing an independent water supply or washing vehicles or equipment Hobby farmers: Reliable stock watering for smaller paddocks or chicken coops Off-grid properties: Lightweight and easy to position in a remote location Emergency back-up: Keeping a reserve supply for households prone to water restrictions

• Schools & community spaces: Safe, BPA-free water for things like veggie patches and drinking fountains
• Properties with limited space: Poly tanks come in a few different model shapes, such as tall, modular and slimline

Steel Liner Tanks (Aqualine): The Heavy-Duty Powerhouse

If you require massive storage volumes or live in fire-prone regions, the Aqualine Steel Liner Tank range is the go to. These tanks are constructed on-site with a galvanised steel shell, and a high-strength internal poly liner.

The Pros:

• Industrial-Scale Capacity: When you need a lot of water, steel is the answer. The Aqualine range starts at 20,000 litres and goes all the way up to 360,000 litres.
• Bushfire Resilience: Steel is non-combustible. In high-risk bushfire zones, a steel tank is often a requirement for fire-fighting reserves. They can be fitted with specialised Stortz fittings to allow local fire authorities to draw water directly from the tank in an emergency.
• Structural Integrity: Aqualine steel liner tanks feature a unique ribbed design for extra strength and heavy-duty galvanised roof trusses. They are engineered to be walked on and can even be custom-designed for high-wind or cyclonic regions.
• Site Versatility: Because they are built on-site from flat panels, they can be installed in tight spaces or behind buildings where a fully formed poly tank simply wouldn't fit through the gate.

The Cons:

• Higher Initial Cost: Due to the volume of materials and the cost of professional on-site installation, the "entry price" for a steel tank is higher than a poly tank.
• Potential for Corrosion: Even with galvanisation, steel can eventually succumb to rust if not maintained correctly, particularly in highly corrosive environments like heavy industrialised zones or direct salt-spray areas.

Best For:

• Large-scale farming: Storing massive volumes for crop spraying or irrigation
• High-risk bushfire zones: Providing a non-combustible water reserve for property protection
• Commercial vineyards: Ensuring a consistent supply for irrigation during the dry seasons
• Livestock stations: Managing the high daily water intake requirements of large cattle or sheep herds
• Industrial warehouses: Capturing high-volume runoff from massive roof areas for site reuse
• Government infrastructure: Providing bulk water for parks, sports ovals or public facilities
• Large rural properties: Where the estate is a larger space with things like a pool, garden and other outdoor uses
• Sites with restricted access: Locations where a large poly tank can't be trucked in, but steel panels can be carried across since it's built on site
• Properties in areas with a Region C rating: Specifically in areas prone to high winds and cyclonic activity

Direct Snapshot Comparison

Poly Water Tanks

• Minimum Capacity: Starts at 660L
• Max Capacity: Up to 46,400L (Bushmans), 47,300L (Bushmans OzPoly North Queensland)
• Best For: Residential, coastal, small-medium rural properties
• Rust Risk: Zero
• Installation: Delivered and placed
• Warranty: 10-year guarantee

Steel Liner Tank

• Minimum Capacity: Starts at 20,000L
• Max Capacity: Up to 360,000L
• Best For: Large farms, fire zones, industrial settings
• Rust Risk: Low
• Installation: Professional on-site build
• Warranty: 5-year guarantee

Key Considerations:

Every Australian property, from homes, businesses and farms has its own set of challenges. From local council regulations to the space you have. Before making your final decision, we recommend asking yourself these four key questions:

How much water do you need?

Its easy to underestimate water usage. Whether you live in a household on your own or with other people, knowing your peak demand is essential. To make this easier, you can use Bushmans Water Tank Calculator to estimate your requirements based on several factors, including the annual rainfall in your location.

What are your local council requirements? Depending on your region, there may be specific rules regarding things like fire-fighting reserves, tank height restrictions or material of tank for new builds. You can find this information on your councils local website, and on Bushman's Australian Water Tank Regulations: State-by-State Guide

What is your sites access like?

A poly tank is delivered as a single, finished unit and requires clear truck access to be placed on its pad (if required). An Aqualine steel tank however, is built on-site from panels - which makes this a flexible option for properties with restricted access or narrow gates.

Is your location prone to extreme weather conditions?

Consider your environment, and your location's annual rainfall. Example, is your main priority a long-term resistance to ocean salt spray, or do you need the structural resilience of a steel tank for a high-risk bushfire zone?

The Final Step: Talk to an Expert

The team at Irrigear has been helping Australians secure their water for decades. Whether you need a 660L slimline for a city backyard or a 360,000L giant for a commercial vineyard, we have the expertise to help you choose.

Talk to one of our team members today to learn more.