How to Choose the Right Size Slimline Tank for Your Home

Choosing the right size slimline water tank isn’t just about how much space you have — it’s about how much water you really need. The right tank size helps you store enough rainwater for everyday use, garden irrigation, or emergencies, without wasting space or budget.

Why Tank Size Matters

Choosing the right size slimline water tank isn’t just about how much space you have — it’s about how much water you really need. The right tank size helps you store enough rainwater for everyday use, garden irrigation, or emergencies, without wasting space or budget.

At Just Tanks NZ, we design slimline water tanks that fit perfectly in Kiwi backyards — whether you’re in Auckland, Tauranga, or Waikato.

Step 1: Understand Your Water Usage

Start by estimating how much water your household uses.

Activity	Average Use (Litres)	Frequency
Toilet flushing	35 L per person per day	Daily
Garden watering	100–200 L per session	Seasonal
Laundry	50 L per load	2–4 times/week

A small household (1–2 people) can often manage with a 1000 L tank, while a family of 4 may prefer 2000–3000 L for comfort and backup supply.

Step 2: Measure Your Available Space

Slimline tanks are designed to fit narrow side passages, behind garages, or along fences.

1000 L StormPanel: Compact (1.35 m length × 1.12 m height) – perfect for small homes or townhouses.
2000 L StormBank: Slim profile with double capacity – ideal for mid-sized sections.
3000 L StormBank: For larger homes or frequent outdoor use.

Make sure to leave a little clearance for fittings and maintenance access.

Step 3: Consider Rainfall & Roof Area

The more roof area you have, the more rain you can capture.
Use this simple formula:

Roof Area (m²) × Rainfall (mm) × 0.9 = Litres of Water Collected

For example:
A 100 m² roof in Tauranga (1100 mm annual rainfall) can collect:
100 × 1100 × 0.9 = ≈ 99,000 L per year.

Even a 1000 L tank will fill quickly — making larger tanks practical for reuse or overflow storage.

Step 4: Plan for Future Needs

Think long-term. You may add garden irrigation, a pool top-up system, or move to partial home water supply later. Choosing a modular slimline design lets you easily add more tanks as needed.

Step 5: Compare Your Options

Tank Model	Capacity	Best For
1000 L StormPanel	1000 L	Small homes & townhouses
2000 L StormBank	2000 L	Medium families & gardens
3000 L StormBank	3000 L	Large properties or rain-reliant homes

All models are NZ-made, UV-stabilised, and come with a 10-year warranty.

Step 6: Check Delivery Options

Just Tanks offers NZ-wide delivery — North Island delivery included, South Island add $150 + GST. Each tank arrives ready for easy installation and plumbing.

Conclusion

The best slimline tank for your home depends on your space, rainfall, and water habits.

Small spaces: 1000 L StormPanel
Families & gardens: 2000 L StormBank
High water use: 3000 L StormBank

Whichever you choose, Just Tanks NZ ensures quality, durability, and local support.