30000 litre Plastic Water Tank

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Big Water Tanks Limited manufactures and sells high quality, potable water, Plastic Water Tanks in Auckland New Zealand. We are proud of the fact that we produce the heaviest tank with the simplest and strongest design - our 30000 litre water tank has a simple, strong dome that is self-supporting. We also use the largest "standard" shot weight of plastic, which makes our wall thickness the greatest.

Our tanks are manufactured on a custom-built, rotational moulding machine with internal temperature logging and a set point for cooking a perfect plastic water tank every time. 

30,000-litre Plastic Water Tank (6,600 Gallons)

    • We offer a full 20-Year Repair or Replacement Warranty (not pro-rata).
    • Our super-tough dome design is the largest on the New Zealand market. The dome has the smallest radius, which gives it engineered support.
    • We have the heaviest standard plastic water tank on the market; at 500kg this is in direct relation to wall thickness and product quality & strength.
    • The tank is available in a range of colours and is designed for potable drinking water.
      • Please contact us should you wish to use this 30000 litre water tank for any other use.
    • Outlet Size: 50mm BSP
    • Manufactured in Auckland, New Zealand.

    Tank Standards

    • Raw Material
      • Type: Medium Density Polyethylene
      • Standard: AS/NZS 2070 - Food Contact Requirements
      • AS/NZS 4020:2005 - Potable Drinking Water
      • AS/NZS 4766 Polyethylene Storage Tanks for Water
    • Manhole access with removable lid
    Diameter 3.78 m (3,780mm)
    Height 3.1 m (3,100mm)
    Weight 500 kg
    Volume 30,000 litres
    Outlet 50mm BSP
    UV Rating UV20
    Compliance Australian food contact requirements (AS2070:1,8) and potable (drinking) water standard AS4020
    • Our tanks can be buried up to 700mm while still retaining their full 20-year warranty. 

    Feel free to contact us should you have any questions or need any further information.


    We have a full range of Accessories to add to your water tank(s) including:  

  • Why Choose Big Water Tanks?

    Big Water Tanks 30,000 litre Water tanks are strong, with a simple design to optimise the most strength, we have the heaviest shot weight of any standard 30,000 litre water tank on the New Zealand Market

    Our Dome

    Our dome has the most curve on the market, that combined with the heaviest shot weight, makes this dome fully self supporting, without the need for a frame to support it.

    Please note, that while we have developed the strongest dome, the tank still needs to be vented. The suction from a pump can cause any dome to collapse if the air cannot move.

    Plastic Material

    Our Plastic is manufactured here in New Zealand to an incredibly high NZ AUS Standard and is suitable for potable water.

    Our plastic resin has been specifically designed as a large tank grade material with the best UV Stabilisation available.

    No Corrugations

    Our tanks have no corrugations or indentations, the reason for this is strength.

    We believe that the corrugations create a weaker tank because they allow for more movement like a piano accordion in a vertical direction creating small stresses at each corrugation.

    In the process of rotational moulding, the corrugations are thinner on the convex curves and thicker on the concave creating an uneven wall thickness through the tank.

    The larger surface area of a corrugated tank means that with the same amount of plastic the effective wall thickness is reduced.

    How does Delivery work?


    Please use the checkout procedure for estimates on freight, we reserve the right to cancel an order if freight is incorrectly calculated by our website, our site cannot calculate some rural areas or island deliveries, we will contact you if there is an issue with a freight costing to your location.

    We deliver Water Tanks throughout the North of North Island, our rates are based on distance, that makes us a bit more expensive for "far away" deliveries we can arrange freight to most islands. Please call us or contact us with your address and details we can confirm the price for the delivery.

    Delivery Process

    Our Delivery prices are subject to our approval and are to the "gate", however we will normally assist putting the tank into its final location if it is safe for us to do so and our vehicles can make the trip, sometimes a digger or crane is required in hard to reach locations.

    Please notify us of any known obstacles-low bridges, low power lines or narrow roads, en route to your property we can decide how to accommodate your delivery before we leave.

    Tanks are pushed off the drivers side of the trailer and land on the base of the tank in a safe location. The tank can be pushed, dragged or lifted into the final installation location.

    How do we Install a Water tank?

    Buried Tanks

    A buried tank needs careful consideration and every situation is a little different, and while our tanks are strong enough to be buried up to 700 mm we recommend that you give us a call to discuss your specific situation.

    Tanks, like swimming pools, can pop up out of the ground if there is no water in them, if a tap in the house is left on in the middle of winter when the ground is very damp, if the tank empties the buoyancy is huge it will lift out the ground and will break connection pipes and mean the tank would need to be reinstalled.

    As a simple guide you cannot bury a tank deeper than the lowest part of your section or natural drainage with a 1:100 fall. So if you have a flat site or section with no falls or that is very flat, burying the tank is not recommended or covered by our warranty in the event of uplift.

    Download our Instructions

    Download a PDF of our installation instructions.

    How Much Water Storage is needed?

    Lets keep this simpl"ish" because there are a large number of factors that increase or decrease water usage.

    An average house is 200m² with an average rainfall of 1200mm that's 240,000 L rainfall a year,

    If you collect all your water (none overflows) that the following per person per year:

    • 1 Person 657L
    • 2 Persons 328L
    • 3 Persons 219L
    • 4 Persons 164L
    • 5 Persons 131L

    The New Zealand water usage average is about 200L per person per day (this is an average not conservative country living.)

    In summer months the average north island water fall is as low as 72mm / month, this can be as low as 10-20mm per month in bad months.

    Our Water Tank can store 30000L of water this with a minimum rainfall of 30mm for 3 months on a 150m² roof is:

    30,000L if full + 30 x 3 x 150 = 43,500L for 90 days of bad weather

    • 1 person 480L
    • 2 Persons 240L
    • 3 Persons 160L
    • 4 Persons 120L
    • 5 Persons 96L

    60,000if full + 30 x 3 x 150 = 73,500L for 90 days of bad weather

    • 1 person 800L
    • 2 Persons 400L
    • 3 Persons 266L
    • 4 Persons 200L
    • 5 Persons 160L

    As a basic rule 1 tank for up to 3 people and 2 tanks for 4-6 people, larger installations of three tanks only help if there is adequate roof collection area.

    Give us a call, drop us an email or message us on the below links so we can assist you with your calculations based on your area and roof.

Customer Reviews

Based on 12 reviews
The delivery could not have gone better

Just want to say thank you for the delivery of our 30K tank, and that Callie is a absolute asset to your company. The delivery could not have gone better.

Highly recommended

An effortless purchase, delivery and instal. Excellent service and follow up. They handled a 30,000litre tank like it was a laundry bucket. Highly recommended

Tania & John
2 x 30,000 Litre tanks

Thank you for the expert recent delivery of our large water tanks. If you are looking for a great product with extremely competitive prices, great communication and prompt service this is the company to deal with. A special mention to Callie our driver who kept us fully informed and went the extra mile to get our tanks off loaded safely. Thanks again team!

Great Service

Thanks to the team at Big Water Tanks. From an easy to read / use website, the first helpful phone call and clear communication via e-mail it has been so easy to purchase and have 2 x 30 000L tanks delivered to our property. Callie the delivery guy was really a pleasure to work with and the water tanks look really great. The price turned out to be good and the delivery lead time was less than other name brands. Thanks again for a job well done.

Great service, great advice, great price

Got put on to you guys through one of the engineers. Have received good service and good pricing, will recommend. Thankyou