Why Your Poly Tank Colour Is More Important Than You Might Think

So, you’ve decided to buy a water storage tank. Once you have chosen your tank size, type and location on your property, it’s time to choose the tank colour. It turns out, there is so much more to poly tank colours than just the aesthetics; although these are important. 

In fact, there’s plenty of science involved in poly tank colours. Tank owners can leverage this science to their advantage when it comes to their water storage. 

We want to help you make an informed, well-rounded decision when choosing your poly tank colour. So, we’ve put together this comprehensive list of considerations to help you choose the best poly tank colour for your property. We’ve broken it down – first diving into how poly tank colours work, then functional considerations and lastly the aesthetic considerations of poly tank colours. 

Read on if you want to make an informed decision when choosing your poly tank colour. 

How Do Poly Tank Colours Work?

Let’s first dive into how poly tank colours are made. 

What Poly Tank Colours Are Made Of

The colours that are used in poly water tanks come from either one pigment or a mixture of pigments. There are two main sources of colour pigments: chemicals created in a lab, or mined minerals. Each production method yields different pigments. The pigment can then be combined with uncoloured polyethylene which is then eventually utilised in rotational moulding.  

How The Colours Are Added 

The polyethylene, colours and additives are initially processed through an extruder. This creates a masterbatch or encapsulated colour. This colour is then added to a carrier resin. 

To create a colour compound, the masterbatch is again combined with the natural coloured polyethylene in an extruder. After, the mix is processed through a mill. This results in a coloured polyethylene powder, which is utilised in the roto-moulding process. 

When adding colours to polyethylene, they must be durable enough so they will not fade when exposed to the high temperatures that occur during the roto-moulding process.

The colours must adhere to the following requirements:  

  • Maintain colour at high roto-moulding temperatures.
  • Resistant to fade in harsh outdoor environments.
  • Must not bleed out onto the mould.
  • Food and water grade plastic where necessary. 
  • Contain no heavy metals.
  • Economical price.
  • Sustainable impact on the environment.


What Poly Tank Colours Are Available

Tanks made from polyethylene generally accommodate the widest range of colours. At Global Rotomoulding, we offer tanks in plenty of colours across the COLORBOND colour range


Many paints may contain solvents and other materials that could leak into the water supply. Therefore colours used in tanks need to comply with government standards for the safe storage of water.  

Functional Considerations

Now we’ll dive into why you should care about your poly tank colour from a practical perspective.  

Algae Contamination

Algae thrive in sunlight. If a tank was painted with an inadequate amount of pigments, this can let in enough sunlight that facilitates algae growth. This can have troubling health concerns. Some forms of algae, like the toxic blue-green algae, are highly dangerous to humans and animals. 

This does not mean that light coloured tanks are a breeding ground for algae. When they are manufactured with an adequate wall thickness by an established manufacturer, algae is effectively prevented.   

It is important to note that algae could be present in a tank with adequate wall thickness if the water is sourced from areas already contaminated with algae. Or, it may occur if the lid of the tank has been left open, letting sunlight in. 

Water Temperature

The colour of the tank can affect the temperature of the stored water too. Pigments will absorb light from the sun and convert the energy into heat. Darker colours will lead to a hotter tank as the day progresses. The tank will also climb to higher temperatures when it is empty.  

Carbon black, which is a pigment used for black or grey tanks, will reach the highest temperature among all of the tank colours (unsurprisingly), reaching up to 63 degrees celsius. 

Other darker colours like phthalocyanine blue and phthalocyanine green can reach between 60-62 degrees celsius. 

Hence, a lighter water tank will store water at cooler temperatures. Generally, this is better for tank owners – especially those caring for livestock. Livestock are more likely to drink cooler water. When our livestock drinks more, they will consume more food, hence increasing their productivity.   

Cooler water may also be necessary across other industries, such as industrial sectors. Here, cooler water is especially pertinent for concrete mixing. It is also required when washing and processing food products. 

UV Protection

UV protection may be a requirement for some tank owners. A process known as photo-oxidation is the primary cause for faded water tanks. Therefore, opting for UV stabilised water tanks that utilise high quality, durable poly resins will help to prevent any damage caused by UV light. 

Choosing an established manufacturer that sells UV stabilised poly tanks is critical to ensure protection from sun exposure.   

Aesthetic Considerations

Once you have considered the functional requirements of your tank, it’s time to consider your aesthetic preferences.

Make It All Flow

If you don’t want your tank to stick out like a sore thumb, opt for a colour that will blend seamlessly with the environment it is placed in. For example, when placing a tank outside a neutral cream or beige coloured home, why not try Classic Cream or Paperbark for the rainwater tank? 

Make A Statement

Perhaps you want to make a statement with your colour choice? You could opt for complementary colours for your house and tank. Complementary colours sit opposite each other on the colour wheel. When together, they pop in a fun and bright way. Common combinations are red and green or orange and blue. We particularly love Mountain Blue, which compliments earthy reds and oranges.  

Pick Up On Accents

If you have accent colours on the eaves, doors or window sills of your home, perhaps choose the same colour for your tank. This gives a seamless finish, without looking too uniform. Rivergum is a common accent without being too bright.

An Aerial View

Alternatively, you may choose to match your tank to your roof. An exact match is easy with Global Tanks COLORBOND colour matched tank colours. 

This makes for a stunning aerial view for those living on a farm where helicopters and planes tend to pass. A common colour choice is coupling a Heritage Red COLORBOND roof with the matching tank.  

When it comes to choosing your poly tank colour, there are perhaps more considerations to make than you’d initially think. This can be overwhelming. But, as long as you’re addressing the functional and aesthetic requirements for your poly tank, you can rest assured you have made the right decision. At Global Tanks, we stock tanks for a diverse range of applications, including Domestic tanks (Slimline, Underground tanks), Rural tanks and tanks for commercial systems (fire services, chemical storage). Our tanks come in up to 30 beautiful, rich colours. Find out more about our range of tanks here, and be sure to contact us if you have any questions. 

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