Thursday, 1 February 2024 Knowledge Articles

7 Risks With Buying a Cheap Rainwater Tank

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When it comes to purchasing a poly rainwater tank, you’ll find prices vary a lot. 

However, it is important to remember that a cheap price can often mean fewer features or poorer quality. This raises the question of what other risks you take when buying a cheap rainwater tank.     


Risk 1: Poor tank design and engineering  

Changes in temperature will cause expansion and contraction of the tank. In addition, the weight of water pushing downwards and outwards varies with the water level in the tank, and the force of the water pushing against the walls of the tank has the effect of pulling the roof downwards.  

In a poorly engineered tank, repeated expansion and contraction over time can result in the loss of structural integrity, distortion of the tank shape, or even collapse.  

While the corrugated design of Promax ENDURO tanks is attractive, its main benefit is the extraordinary strength of the tank wall design which, when integrated with the engineered roof profile, ensures rigidity, stability and strength.      


Risk 2: Cheaper, substandard raw materials

The choice of raw materials and the processing methods used have a major influence on the overall quality of a poly tank. Promax blend and process their own raw materials. This combination of high-quality materials and meticulous processing aligns perfectly resulting in a premium tank manufacturing process.  

In contrast, cheap tank manufacturers that purchase pre-blended raw materials lack control over production, and you are taking a gamble on the quality of the final product.


Risk 3: Inferior manufacturing equipment

Promax tanks are made by a process known as rotomoulding or ‘cooking’. Polyethylene powder is placed in a mould and the mould is rotated while heat is applied through the walls, and the tumbling powder gradually melts. The molten polyethylene adheres to the mould and forms a smooth layer of uniform thickness over the inside surface.   

Promax has continually invested in the most modern and up-to-date equipment that ensures the precise control of temperature that is critical to the cooking process. A manufacturer that has not made a similar investment in equipment will have poorer temperature control and is likely to produce an inferior product.     


Risk 4: Rushed cooling processes can reduce product quality

Once the molten polyethylene has been accurately placed within the mould, it must be carefully cooled. Why is this important?   

The polyethylene in moulded water tanks has a crystalline structure. Slow cooling results in larger crystals whereas fast cooling results in smaller crystals. Cooling is critical to this structure.   

Carefully controlled cooling results in uniform crystal size and optimises the physical properties of the finished water tank. Rushed cooling results in a more brittle product that is more likely to crack or fail.  

In a busy factory, it’s sometimes tempting to cut corners. While the manufacturer benefits from producing more tanks, the buyer risks a lower quality product. Promax understands the pitfalls of a hurried process and has the patience to manufacture a high-quality tank. 


Risk 5: Unexpected charges for accessories, fittings and fixtures   

To reduce costs, some manufacturers will reduce the standard features of the tank. Not every tank is supplied with the same fixtures and fittings, and many suppliers charge extra for features that are standard on other tanks. Promax ENDURO tanks are available in a range of 7 colours and are fully featured to include inlet panels for ease of installation and threaded base outlets. 


Risk 6: Your warranty may be worthless

Very few buyers take the time to read the warranty’s terms and conditions when making a purchase. Manufacturers or resellers of inferior products may modify their warranties to limit or eliminate a customer’s ability to make warranty claims. Promax offer products with a dependable warranty that you can trust. Additionally, Promax’s extensive reseller network ensures that reliable after-sales support is readily available. 


Risk 7: Poor customer support

With so many options available, it is essential that you get the right advice and select the tank that is best suited to your needs. Promax have a dedicated team of customer service experts, and an extensive reseller network to answer your questions, and help you get the right tank for your needs.  

Promax also has an industry-leading library of online resources to ensure you can make informed decisions about products, installation, and accessories.  


An obsession for detail and absolute control over the entire manufacturing process ensures that Promax produce a water tank of exceptional quality that will stand the test of time. Water where you need it and when you need it, with the confidence of a Promax tank. We believe that Promax offers New Zealand’s most robust, durable, and longest-lasting water tank.    

If you want to know more, talk to our expert team on 0800 77 66 29 or email with your enquiry.