1. Why should I choose a tank that meets AS/NZS 4766 standards?

A tank that is certified to AS/NZS 4766 standards provides independent assurance of the claim by the manufacturer that products comply with this Standard. This means that our certified tanks come with the independent assurance that:

  • they have been properly designed and manufactured to last the length of their warranty life of 20 years
  • they have been manufactured using food grade polyethylene which means that the water stored in it is clean and safe to drink
  • quality processes are in place to ensure that we will reliably produce the same quality product each time

2. What does AS/NZS 4766 mean?

The AS/NZS 4766 standard specifies requirements for the design and manufacture of polyethylene storage tanks that are rotationally moulded in one-piece seamless construction, for non-buried, vertical installation, and capable of containing water, liquids for food and beverage manufacture and chemical solutions at atmospheric pressure.

To be assured of the structural integrity of your poly tank, it is very important that you confirm your tank is made to meet or exceed this standard.

3. What tests do you carry out to ensure my tank is compliant with AS/NZS 4766 standards?

The AS/NZS 4766 standard requires that the manufacturer pass a strict set of tests. Some specified requirements that you can physically look for include:

  • Your poly tanks must be constructed as one piece (there should be no side seams)
  • Radius of rim around tank’s base must be a minimum of 25mm for tanks up to a 1.8m diameter
  • Tanks over a 1.8m diameter must have a minimum base radius of 38mm
  • An installation guide must be supplied with your tank
  • A tank serial number to be marked on your tank
  • Manufacturers name or registered trademark.
  • Tank capacity, based on the fluid level used in the design criteria.
  • Maximum SG (specific gravity) of contents of tank
  • Maximum design service temperature, e.g., 23deg cel.
  • Certification license number.
  • No section of the tank should be thinner than 4.5mm.
  • Product certification logo.

4. What is the difference between ISO Type 5 AS/NZS 4766 standards and an ISO 9001:2015 Quality Manufacturing System?

The ISO Type 5 AS/NZS 4766 relates to the physical product and what is required to manufacture to this standard. The ISO 9001:2015 Quality Management System relates to business processes. 

Within the ISO Type 5 AS/NZS 4766 standard there are many aspects regarding material requirements (mechanical and chemical properties), design requirements (minimum dimensions for walls, mechanical design, volume), practical requirements (overflows, venting, outlets) and testing. 

ISO 9001:2015 is a general management system It looks at any business and applies good business practices around the different processes that are followed in an organisation.

5. Do your tanks contain any BPA’s?

No – ALL Rota Tanks are BPA free.

Our tanks are made from virgin food grade polyethylene.  Bisphenol A (BPA) is not used as a component in the manufacture of polyethylene.  BPA is primarily used in polycarbonate and in epoxies used to line cans.  Polyethylene does not leach chemicals and has been used for direct food contact for many years.

6. How do I keep debris etc contaminating my stored water?

All Rota Tanks come fitted with a rust proof screen ay all outlet points. This prevents foreign objects, dirt and debris from getting into the water. It also prevents mosquitoes from breeding in this stored water.

These screens are removable and replaceable as well in case of damages. 

7. Why should sunlight not get inside a water tank?

Sunlight encourages the growth of algae – which will contaminate the water you have stored in your Rota Tank, making it unsuitable to consume. Rota Tanks are manufactured using UV stabilised material as well as tested to ensure no sunlight can get inside your tank.

8. Is there uv protection in the resin you use?

Rota tanks are moulded from polyethylene compounded with the latest technology in ultraviolet (UV) light stabilizers.  The UV stabilizers will reduce the harmful effects of ultraviolet light exposure and are intended to extend the lifetime of a tank over similar materials that are not compounded with stabilizers.  

Our tanks are made with UV20 material meaning 20,000 hours of exposure to the sun, there will be 50% of UV protection remaining.  This rating also needs to consider location and prolonged exposure to the sun.  

9. Does the colour of a tank give any indication as to the quality of the tank?

All Rotomould tanks are manufactured from polyethylene compounded with ultraviolet (UV) stabilizers.  The UV stabilizers will reduce the harmful effects of ultraviolet light exposure and are intended to extend the life of a tank over similar materials that are not compounded with stabilizers. 

The standard colour for most of our tank is MIST GREEN.  All tanks may be ordered in non-standard colours such as black, dark green or (white semi-transparent) as an option. Semi-transparent or translucent tanks may not be given full warranty as all other opaque tanks have.  The colour of the tank does not increase the life expectancy or UV resistance of a tank. 

10. What is the thickness of your tanks?

The minimum thickness for every tank produced is at least 4.5mm at any location for sidewall, roof and at least 3.5 mm at the base.

Thickness varies from the top to the bottom of the tank depending on the capacity. 

11. How do I know when my tank was made?

All Rota tanks have the following serial numbers punched on the neck of the tank.

Factory code; tank code; manufacturing date; the sequence of tank produced E.g. 1A 12/12/12-12

These codes enable us to trace what batch of material your tank was made from, who the operator was, date/time of manufacture etc. 

12. What materials are used to manufacture Rota tanks?

All Rota tanks are manufactured using virgin (not recycled) food grade LLDPE (Linear Low-Density Polyethylene) resin which is compliant with the AS/NZS 4766: 2006 standards. 

13. Why do Rota Tanks have internal facing lines?

All Rotomould tanks have inward swedging which acts like the ribs of human. It binds up the tank and provides strength in storing water.

14. How many years warranty do you provide?

We provide 20 years warranty on our tanks, subject to certain criteria being met. Click here to download a copy of our warranty.  No warranty is provided on seconds tanks and this will be highlighted to you during the sales process. 

15. Are Rota Tanks suitable for storing timber treats, fertilisers or biodiesel?

No, Rota Tanks are designed for water storage only.  They are not rated to contain chemicals or fertilizers.

Storage of diesel (or any other chemical) in a polyethylene tank is different from the storage of water.  The polyethylene walls of the tank are softened by contact with the diesel. This needs to be accounted for by choice of polyethylene grade, design and wall thickness. So simply we do not recommend our valued customers to store diesel in polyethylene tanks.

16. What are drill points on your tanks?

Drill points are a moulded in feature of a tank used as a quick locating point for fittings.  Drill points are typically located in standard fitting locations only.  For tanks ranging from 3000lt to 10000lt, the fittings locations are bit higher than the bottom knuckle radius of the tank or around 140mm from the base. This is to avoid the dirt and sludge into your water supply system.

17. Can your tanks be pressurised?

No, our tanks cannot be pressurized or exposed to vacuum.

18. Will freezing temperatures will have any impact on my Rota Tank?

Freezing temperatures will not have any effect on a polyethylene tank, however, if you plan to keep a liquid in the tank that you know will freeze, be sure to leave sufficient room for expansion.  Be aware there is a greater chance of a polyethylene tank cracking during transportation in cold temperatures.

19. What is the purpose of overflow and breathers on tank?

The tanks will be pressurised if there is no overflow installed and may burst as it spots its weak point.

Pressure/Vacuum Relief Valves also are known as breather are used extensively on bulk storage tanks, to minimise evaporation loss. The Valves prevent the build-up of excessive pressure or vacuum which can unbalance the system or damage the storage vessel.

20. How can I secure my tanks in case of strong winds or cyclones?

All Rota Tanks’ ranging from 2000lt to 10000lt have tie holes on the roof of the tank, tie the rope or wire on those holes and on the base hook and hand tie it. Do not use block and tackle to tight the wire or rope.

21. Can I paint my tank?

Although there are products being marketed that claim to have successful adhesion to polyethylene, we do not support this practice.  Paints with adhesion promoters will work for only a limited time before peeling is experienced.  Polyethylene has a high thermal coefficient of expansion and contraction and this causes adhesion failure.

22. What type of surface is required for placement of a water tank?

A solid concrete base is required with a smooth surface. Customers who are willing to make the base out of iron please ensure it is stacked without leaving any space in between. Remember before placing the tank on the base check for any objects which may create a stress point to your tank. 

23. Are rota tanks repairable through plastic welding?

Yes, polyethylene tanks can be repaired through plastic welding by qualified personnel.

24. Can a septic tank be used for portable water storage?

No, drinking water can only be stored in our water tanks. 

25. Can I use septic tank above ground?

Our standard septic tanks are designed for below ground use only. From a hygiene perspective we recommend that tanks are kept underground. 

26. Can I have more than one fitting on the sidewall of a Rota Tank?

Yes, more than one fitting is permitted. The normal factory fitting will be installed on the opposite side of overflow or on the logo side on the outlet zone. Prior to adding any additional fittings please consult with our team for advice.

27. Do you deliver?

Yes! Whether you are in Fiji, Solomon Islands, Tonga, Samoa, Vanuatu or Kiribati we have delivered tanks to your region and we will deliver for you.