Help Center

Big Water Tanks is the newest of the large water tank manufactures in the New Zealand Market, and this is why we do things a little bit differently...Browse the below points to find out more about our tanks.

Our 30,000l tanks are strong, we have a simple strong design with the largest standard shot weight of 500kg of plastic.

Dome

• Our dome has the most curve on the market and will not sag or collapse, 
• It is fully self supporting, not needing any additional frames to hold it up 

Wall thickness

• Our tanks have an average wall thickness of 12mm
• We have developed our machine to allow for a ticker wall thickness around the base of the tank where the pressure is greater
• We have highly advanced internal temperature monitoring ensuring every tank is manufactured to the highest standard, we don't rely on time allocation to cook our product 

Plastic Materials

• 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 an accordion in a vertical direction creating small stresses at each corrugation 
• In the process of rotational moulding 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 

We only manufacture one product, our business model is simple and reliable, we strive to make the best product in the best way without the added head ache of 100+ different products to manufacture.

We did alot of market research and per $ the 30000 litre tanks is the most economical and the most common tank on the market.

Our Warranty is the best on the market, we do not offer a pro-rata warranty but a full repair or replace 20 year warranty. providing the tank installation was done correctly.

Our online registration makes sure of that we want to ensure you do not have a problem with your tank any time in the future, we even request installation photos and would come out and check to see is it meets the standard if we feel there are any issues.

Shipping Pricing for 30,000 l Water Tanks

Auckland: 

1 Tank - $110.00 Each
2 Tanks - $66.00 Each ($132.00)

Northland, Bay of Plenty, Waikato

1 Tank - $400.00 Each
2 Tanks - $300.00 Each ($600.00)

Gisbourne, Hawkes Bay and Taranaki

1 Tank - $950.00 Each
2 Tanks - $600.00 Each ($1200.00)

Please call us for delivery further or to islands or ferry crossings as these are not included

We Deliver throughout the 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

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 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 accomdate your delivery before we leave.

A buried tank needs careful consideration and every situation is a little different, 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. Things to consider:

Uplift

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. Our installation guidelines are as follows:

Instructions:

Hole Preparation:

Dig the hole 100mm deeper and about 4m Diameter (100mm bigger than the tank), taper the walls with a 10° slope or greater if the soil is loose. It is recommended to put a retaining cloth or even weed-matting around the cut face to prevent erosion.

Tank Drainage Preparation:

Install a 100mm socked drainage coil around the edge of the hole and run that into a lower drain at a fall of at least 1:100

Tank Base Support:

The Bottom of the hole should be filled with GAP7 Stone (metal) and be well compacted, if the surrounding soil is very clay like and or does not drain too well the outer edge (by the drainage coil) can be replaces with scoria to allow for better drainage with a little metal over the top. 

Drain Trench:

The trench should be back-filled with scoria to allow water to drain away.

Install the tank:

Drop the tank into the hole and centre it. Back-fill the sides of the hole with Bark this does not need to be compressed and is there to stop children and items from falling into the hole. Install a water outlet connection above ground level with a flexible hose using a tank compression fitting. Connect the gutters to the tank as per other instructions.

Lets keep this simple"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 thats 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

60,000L if 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 we can assist you with your calculaations basd on your area and roof.