selecting the right material for your tank

How to Select the Right Material for Your Rainwater Tank

Here in Australia, we have quite a few cultural icons. Koalas, Bondi Beach, barbecued snags, and even the good old Hills Hoist… they all are intrinsically Australian. 

Also among the list is the good old corrugated metal rainwater tank. Although less of a common feature these days, 20 years ago they were a staple of many semi-urban and country properties. 

While functional, these old metal beasts weren’t overly attractive. Fortunately, today there are many more options for rainwater tanks. They come in various sizes, colours, and materials to suit any kind of space. 

But with this new range of choices, each comes with its own advantages and disadvantages. So how do you decide which material is right for your household’s rainwater tank? 

Let’s quickly run through the major choices.

Polyethylene water tanks

Polyethylene is a UV stabilised, food-grade plastic. It’s a popular choice for rainwater tanks for many good reasons:

  • They’re strong, light-weight and cheaper than other materials
  • They can be moulded into all sorts of sizes
  • Their durability and lightweight makes them easy to install
  • They come in a range of colours that can match your taste
  • They are non-corrosive so won’t taint your rainwater supply

While polyethylene tanks are certainly an attractive choice, they do have one drawback. Rainwater is naturally acidic and if you have copper pipes, the acidity can cause copper to leak into your water if it’s left in the pipes for some time. 

Concrete and steel tanks both leak minerals into the water that reduces water acidity. But polyethylene’s plastic properties don’t offer this counter-balance. So if you have copper pipes, you need to apply proper filtration to avoid this leakage. 

Additionally, another drawback of poly tanks is that polyethylene is a plastic that will take generations to break down, releasing toxins as it does so. Still, they can be recycled after 15 years. 

Steel water tanks

Most steel water tanks are made of galvanised steel, which means that the steel is coated with zinc to protect it from corrosion. These tanks are suitable for large storage requirements, as they are extremely strong and can hold capacities of anywhere between 30,000 to millions of litres of water. 

However, over time galvanised steel rusts and corrodes, and the zinc can leak into the water. Colorbond tanks have baked-on layers applied to the steel (including polyester primer and paint) to stall the corrosion process. 

While most steel tanks only last around 5 years – especially if they are out in extreme weather – it’s this extra protection that makes Colorbond last for up to 20 years. Stainless steel tanks don’t have this issue, but they can be quite a lot more expensive.

Concrete water tanks

Concrete rainwater tanks can be installed either above or underground, which makes them a good option if you’re short on space. They can also be constructed to allow for load-bearing, such as under a driveway. 

As you’d imagine, concrete is very heavy, so the tanks are poured on-site, or delivered in sections and cemented together. Concrete does leak lime over time, and you’ll have slightly alkaline water. A polyethylene lining can be used to stall this process. 

One other issue with concrete tanks is that reinforcing steel into concrete can affect the durability of the tank. Concrete is porous, so over time the water can seep in and corrode the reinforcing steel, causing the tank to crack and break.

Fibreglass water tanks

If you decide on a fibreglass tank, you’ll need to make sure it has a food-grade coating to be up to Australian water-storing standards. Fibreglass is very stiff and rigid, but also thin and light, which makes them brittle and easy to crack. 

They also let more light through, which can accelerate algae growth. Still, it is another long-lasting option that can be installed above or below ground. The good news with fibreglass is that this material resists corrosion.

Choosing the right tank material for your property

It’s great to have so much choice these days. But as you can see, there are advantages and disadvantages with each type of tank material, so it’s a matter of working out your needs, your budget, and then finding a happy medium. 

An important factor to consider is not just the initial outlay cost, but how much you anticipate the tank will need upkeep and replacement over the years. Choosing a cheaper tank can become quite expensive over the long term. 

Feel free to give us at ASC Tanks a call on 1300 220 606 to discuss the right material for your tank. We have been in the tank business since 2007, and have seen it all! Alternatively, drop in to see us at our showroom in Hallam VIC, and check out some of the options for yourself.

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