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Steel vs Poly Water Tanks

Steel vs Poly Water Tanks

Which is better?

The answer? As always - it depends.

There are distinct advantages for each, and it depends completely on your requirements, available space, budget and taste.

Which is better quality?

Neither is a higher quality than the other. We only source our products and materials from manufacturers who have been in the industry for at least 15 years and have a proven track record. The material isn't as important however as the company producing the item. 

There are some important things to consider when choosing your water tank and it's not a simple question of which is better.

One of those considerations can be the placement of your tank. It is ideal to place your tank close to your rain catchment area. This makes the piping required to fill your tank significantly more simple, efficient, and cheap. Where the tank is located can also affect the lifetime of the materials.

Ideally you would want to locate the tank in the shade, partially to keep the temperature of your stored water – and therefore water evaporation, down. But also some water tank materials, most notably polyethylene and fiberglass, will degrade faster with direct sunlight.

What's so good about steel water tanks?

Steel water tanks have come a long way over the past century. Where in the past they were made from galvanised steel and soldered together - this is now a very outdated practice. 

BlueScope has developed a type of steel called "Aquaplate". Aquaplate is a type of steel that is laminated with a polymer liner that creates a separation barrier between the bare metal and the water - making modern steel water tanks rust proof.

So the longevity of steel water tanks is not in question at all. You'll still see old, galvanised tanks that are decades old (although they're probably starting to rust). That is without utilising Aquaplate (which all modern manufacturers use).

Steel water tanks come in a much wider range of sizes than poly tanks. This means you can have your steel water tank made to your measurements. This gives you a huge amount of choice which can be invaluable when you have limited space on your property such as in suburbs and city dwellings. We can manufacture a tank to make maximise the water storage with your available space.

Steel water tanks can also be repaired without too much trouble. 

Our steel water tank range comes with a 20-year warranty against corrosion and a 10-year workmanship warranty.

What's so good about poly water tanks?

Thanks to modern manufacturing methods - poly water tanks are easy and cheap to produce. This passes directly onto the consumer who now can pay much less for a water tank. Especially in a situation where you don't have a choice but to buy a water tank (BASIX requirements).

This is the biggest advantage for poly water tanks. 

Poly water tanks have also come a long way over the past few decades. Most of the dodgy operators have since gone out of business and you're only left with the reputable manufacturers who will honour their solid warranties. 

On top of that, poly tanks tend to be UV stabilised these days - which means they won't break down in the sun nearly as quickly as the earlier models. However, there is a limit to how much UV inhibitor can be added to the polyethylene while being fit for potable water storage so degradation will still occur, but not to the rate of earlier water tanks.

Our poly range comes with a 20-year fix or replace warranty.




We like to keep it positive but there are a couple of negatives to both of these water tank types.


  • More expensive than similar capacity poly water tanks.
  • Delivery can be tricky if access is poor.


  • Less size flexibility - There are only a few set sizes for certain capacities
  • Larger footprints (they take up more space) than steel water tanks, leading to less capacity in the same physical size.
  • Once a poly water tank has degraded to the point it can not hold water any longer, there are extremely limited recycling options available – With it most likely ending up in landfill

Any disadvantages however are most definitely outweighed by the many positives of owning your own water supply. 

Whichever you do decide to go with - you've made the right decision.

At the end of the day, it's a matter of preference, budget, available space and location for your water tank.