In the world of rainwater harvesting, slimline water tanks are a popular choice for urban and regional Australians alike. With their space-saving design and sleek appearance, they fit comfortably along side paths, behind sheds, or under eaves—making them perfect for smaller properties or modern homes with limited yard space. But once you’ve settled on a slimline style, the next big question is: What size is right for you—2000 litres or 5000 litres?
This expert guide compares the two most popular slimline sizes, exploring their dimensions, cost, use cases, and return on investment. Whether you’re watering a garden or supplying your entire household, this comparison will help you make the right decision.
Understanding Slimline Water Tanks: Why They’re So Popular.
Slimline tanks are specifically designed for narrow spaces where traditional round tanks won’t fit. They’re ideal for homeowners, builders, or renovators who need water storage without compromising on outdoor area or property access. Unlike bulky round tanks, slimline water tanks:
- Are ideal for installation beside fences, down side alleys, or next to garages
- Provide clean, practical water storage for rainwater harvesting
- Can still deliver thousands of litres of storage capacity
At The Water Tank Factory, our Upright Urban Slimline Water Storage Tank is manufactured from durable, food-grade polyethylene with superior wall thickness thanks to a higher shot weight per tank—something many cheaper competitors don’t offer.
2000L Slimline Water Tank Overview
Tank Factory Model: 2000L Upright Urban Tower Tank
Dimensions: 625mm Width x 2250mm Length x 1930mm Height
Shot Weight: 100kg
Price: $1,160 (factory-direct pricing)
Best For:
- Small backyards and urban homes
- Garden irrigation and occasional outdoor use
- Homeowners with limited side access
Why Choose It:
This compact tank offers generous water storage in a narrow footprint. It’s ideal if you want to start harvesting rainwater without overcommitting to a larger system. At just 625mm wide, it fits comfortably down most side pathways. It’s also easier to install due to its lighter weight and smaller excavation requirements if set against a building.
5000L Slimline Water Tank Overview
Tank Factory Model: 5000L Upright Urban Slimline Water Tank
Dimensions: 940mm Width x 3080mm Length x 2170mm Height
Shot Weight: 250kg
Price: $2,350 RRP — Now only $1,875 during our Winter Special
Best For:
- Families with higher water usage
- Flushing toilets, washing machines, garden and lawn irrigation
- Homeowners wanting to meet BASIX or sustainability requirements
Why Choose It:
If you’re planning to use rainwater for multiple indoor or outdoor purposes, 5000L is the most efficient choice. It offers 2.5x the storage capacity of a 2000L tank for only $715 more during the Winter Special. With a wider footprint and heavier shot weight, this tank is engineered for strength, durability, and long-term performance.
2000L vs 5000L: Cost Per Litre Comparison
| Feature | 2000L Tank | 5000L Tank |
|---|---|---|
| Capacity | 2000 Litres | 5000 Litres |
| Price | $1,160 | $1,875 (Winter Special) |
| Cost per Litre | $0.58/L | $0.38/L |
| Dimensions (W x L x H) | 625mm x 2250mm x 1930mm | 940mm x 3080mm x 2170mm |
| Shot Weight | 100kg | 250kg |
| Footprint | Compact | Requires more space |
Verdict: The 5000L tank offers far better value per litre—and with the current Winter Special, it’s a highly cost-effective long-term solution for households seeking larger water storage.
What Size Tank Do You Actually Need?
Things to consider:
- Average annual rainfall in your area
- Roof catchment area (1mm of rain per m² = 1L of water)
- Intended water use (garden, laundry, toilets, etc.)
- Available space on your property
- Council or BASIX requirements for new builds or renovations
If you’re only watering a small garden or topping up a pool occasionally, 2000L may suffice. But if you’re aiming to reduce mains water dependency, 5000L is a smarter investment.
Shot Weight Matters: The Hidden Quality Difference
One of the most overlooked factors in choosing a slimline water storage tank is shot weight—the amount of material used to manufacture it. A higher shot weight equals thicker walls, greater structural integrity, and longer life.
- The Tank Factory’s 2000L tank has a 100kg shot weight
- The 5000L tank boasts a 250kg shot weight
This is superior to many competitors, including Bushmans and Tank World, whose tanks often have lighter specifications and shorter warranties.
Installation Tips for Slimline Tanks
- Level and compact base: Use crusher dust or a concrete pad
- Accessibility: Ensure there’s space for maintenance, downpipes, and pumps
- Overflow and first-flush diverters: Keep your water clean and safe
- Tank connectors and taps: Upgrade for easy garden hose attachment or system integration
The Water Tank Factory also provides expert advice and accessories to simplify your setup.
Why Choose The Water Tank Factory’s Slimline Water Storage Tank?
- Made in Australia for Aussie conditions
- 10+10 year warranty on all poly tanks
- Highest wall thickness in the industry due to superior shot weight
- Factory-direct pricing (no middleman)
- Australia-wide delivery
Explore the full range of Slimline Water Tanks at:
https://www.watertankfactory.