Corrugated Water Tanks

In the vast landscape of Australian water storage, few sights are as iconic as the round, corrugated water tank. For generations, these structures have stood as silent guardians of our most precious resource. However, as technology has evolved, so has the engineering behind these tanks.

At Polymaster, we have taken the traditional corrugated aesthetic and fused it with advanced polymer science to create a product range that is practically indestructible, aesthetically versatile, and exceptionally safe for drinking water. This guide explores everything you need to know about corrugated poly tanks, from the physics of their design to choosing the perfect model for your property.

1. The Science of Corrugation: Why Ribbed Walls Matter

At first glance, the horizontal ribs on a Polymaster tank might look like a simple design choice. In reality, this is a feat of structural engineering known as hoop strength.

Understanding Hoop Strength

When a tank is filled with water, the liquid exerts an immense amount of outward pressure on the walls. This pressure is greatest at the bottom of the tank.

• The Accordion Effect: Without reinforcement, a flat-walled plastic tank would “balloon” or bow under the weight of the water.

• Structural Ribbing: Corrugation acts like a series of internal belts. These ribs distribute the outward pressure evenly across the surface area of the tank, preventing deformation and significantly extending the lifespan of the polymer.

• Self-Supporting Roofs: Because the walls are so rigid, our tanks do not require internal support poles. In traditional tanks, these poles can become points of failure or areas where sediment and bacteria collect.

One-Piece Moulding Technology

A critical differentiator for Polymaster is our rotomoulding process. Many competitors join two halves of a tank together, creating a vertical seam. Under the pressure of 22,000+ litres, a seam is a liability. Polymaster tanks are moulded as a single, seamless piece of polyethylene. When you combine a seamless build with a corrugated profile, you have a tank that is engineered for extreme longevity.

2. Material Excellence: More Than Just Plastic

Not all “poly” is created equal. The longevity of a water tank depends entirely on the quality of the resin and the additives used during manufacturing.

UV+ Double Strength Protection

The Australian sun is the primary enemy of outdoor plastics. UV radiation can cause inferior plastics to become brittle and eventually crack (a process known as photo-degradation).

• Polymaster’s Defense: We use an exclusive UV+ double-strength resin. This material is specifically formulated to withstand the high UV index of the Australian climate, ensuring the tank remains flexible and strong for decades.

Food-Grade and BPA-Free

Whether you are watering your organic kale or providing drinking water for your family, the purity of the water is paramount.

• AS/NZS 4020 Certification: Our tanks are tested and certified for the storage of potable (drinking) water.

• No Leaching: The high-quality polyethylene used by Polymaster is BPA-free and does not leach chemicals into your water supply, even after years of exposure to the sun.

3. Product Range: Finding Your Perfect Fit

The Polymaster range is divided into categories based on capacity and footprint. Below is a comprehensive look at our corrugated offerings.

Small Capacity Round Tanks (The Suburban Range)

These tanks are designed for urban environments where space is at a premium but water security is still a priority.

Medium Capacity Round Tanks (The Residential Range)

These are the most popular choices for modern Australian homes looking to offset their water bills and meet council requirements.

Large Capacity Round Tanks (The Rural & Agriculture Range)

For those on acreage or working farms, water is a critical asset. These tanks offer massive storage potential with the same corrugated strength.

4. The Aesthetics: Matching Your Lifestyle

A water tank doesn’t have to be an eyesore. Because Polymaster tanks are made from high-quality polymers, we can infuse the resin with a wide palette of colours that match the standard Australian building landscape.

COLORBOND® Integration

Our tanks are available in over 20 authentic COLORBOND® colours. Whether you want your tank to pop as a feature or disappear into the background, we have the shade:

• The Modern Look: Monument and Ironstone are perfect for contemporary builds with dark trim.

• The Coastal Look: Shale Grey and Windspray blend beautifully with light-coloured brickwork and seaside environments.

• The Rural Look: Pale Eucalypt and Paperbark are designed to vanish into the Australian bushland.

5. Installation Essentials: Setting Your Tank Up for Success

Even the strongest corrugated tank will underperform if it isn’t installed correctly. Here is a guide to ensuring your Polymaster tank lasts its full 20+ year lifespan.

The Foundation

The most important step is the base. A full 22,500L tank weighs over 22 tonnes. If the ground shifts, the tank can be damaged.

1. Level Ground: The site must be completely level and stable.

2. Concrete Pad: A reinforced concrete pad (approx. 100mm thick) is the gold standard for large tanks.

3. Crushed Dust/Sand: For smaller tanks, a compacted bed of crusher dust (free of large stones) is often sufficient. It should be at least 100mm larger than the diameter of the tank.

Plumbing and Pipework

• Flexible Couplings: This is a vital but often overlooked step. As the tank fills and empties, it will slightly expand and contract. You must use a flexible hose or coupling between the tank outlet and your hard-plumbed pipes. Without this, the movement of the tank can snap the fittings.

• Inlet Strainers: Always ensure the leaf strainer is securely fitted to prevent mosquitoes and debris from entering the water.

6. Maintenance: 15 Minutes to Longevity

One of the best features of a poly corrugated tank is how low-maintenance it is. Unlike steel tanks, there is no risk of rust or corrosion. However, a little care goes a long way:

• Quarterly Strainer Check: Remove any leaves or twigs from the top strainer.

• First Flush Diversion: We highly recommend installing a “First Flush Diverter.” This simple device ensures the first few litres of “dirty” rain (containing dust from your roof) are discarded before the clean water enters your tank.

• Annual Sludge Inspection: Every 2–3 years, check the bottom of the tank for sediment. If a layer has built up, it can be siphoned out or professionally cleaned to ensure your water quality remains high.

7. Environmental Impact: Why Rainwater Harvesting is a Duty

By choosing a Polymaster tank, you are contributing to a broader movement toward water sustainability in Australia.

• Reducing Urban Runoff: In cities, heavy rain hits hard surfaces and rushes into stormwater drains, often carrying pollutants into our oceans. Tanks capture this water, slowing down the flow and reducing erosion.

• Saving Energy: Pumping water from dams to your house requires massive amounts of electricity. Using gravity or a small local pump to move water from your tank is significantly more energy-efficient.

• Drought Resilience: As Australia faces increasingly unpredictable weather patterns, having a personal “bank account” of water can be the difference between a dead garden and a thriving one during a drought.

8. Why Polymaster? The 20-Year Promise

We don’t just sell tanks; we provide peace of mind. Every one of our corrugated round rainwater tanks comes with a 20-year warranty. This isn’t just a number—it’s a reflection of our confidence in our Australian-made products.

When you invest in a Polymaster tank, you support local manufacturing and get a product designed specifically for the unique challenges of our climate. From the smallest 200L unit to the massive 50,000L rural tank, our commitment to quality is woven into every rib of the corrugation.