Underdeck water tank prices at The Water Tank Factory start at $1,150. That’s for the 1,000-litre UD1000. Prices run to $3,425 for the 5,000-litre LUD5000, with two other models in between. The right size depends on how much space you’ve got under your deck or house, and how much storage you actually need. Here’s the full breakdown.
Underdeck Water Tank Prices at a Glance
Freight is a flat $195 across the range for standard delivery areas. That’s on top of the tank price, so factor it into your budget from the start.
There’s a jump in the price-per-litre as you move up the range. The UD1000 works out to roughly $1.15 per litre. The LUD5000 comes in closer to $0.69 per litre. Bigger tanks make better use of your space, litre for litre — the trade-off is a higher upfront cost and a trickier install.
Which Underdeck Model Suits Your Space?
Underdeck tanks solve a specific problem: you’ve got dead space under an elevated home or deck, and you want to put it to work. However, the four models in the range aren’t interchangeable — each one suits a different footprint.
The UD1000 is the most compact option. It measures 1,200mm wide by 1,720mm long, so it slots into tight single-pier gaps. If you need more storage than one tank offers, you can connect several UD1000s together and build capacity gradually.
The UD2000 runs a slimmer profile — 1,200mm wide by 2,350mm long. It’s designed to fit between the piers of an existing deck, which makes it a common retrofit choice for homes built before rainwater harvesting was front of mind.
The LUD3000 and LUD5000 are the Lattice™ models. They’re built for small blocks carrying a large home, where the footprint under the house is your only real storage option. Both need lifting equipment on delivery day, given their weight — the LUD5000 has a 250kg shot weight. Talk to our team about site access before you order one of these.
Why Underdeck Tanks Cost More Per Litre Than Round Tanks
If you’ve compared these prices to a round tank, you’ve probably noticed the gap. A round tank can land under $0.50 per litre at larger capacities. Underdeck tanks sit higher, and there’s a straightforward reason for that.
Underdeck tanks use a patented low-profile design. That shape is what lets a tank slide into a gap as shallow as 710mm, but it also means more material and more engineering goes into every litre of capacity. You’re paying for the shape, not just the water it holds.
That’s the trade-off. A round tank stores water efficiently. An underdeck tank stores water invisibly — and for a lot of suburban blocks, that’s the only option that works at all.
What’s Included in the Price
Every underdeck tank price above covers the tank itself, built to order at our Alstonville factory. Freight is a separate flat-rate charge, and it’s the same $195 across all four models.
A few things sit outside the tank price:
A few things sit outside the tank price:
- Plumbing and installation — connecting the tank to your roof catchment and household plumbing is a separate job, usually handled by a licensed plumber.
- Lifting equipment — required for the LUD3000 and LUD5000 on delivery. Confirm site access with our team before ordering.
- Pumps and accessories — if you’re plumbing the tank in for household use, you’ll need a pump. Browse our pump bundles to see what pairs well with an underdeck setup.
As the online sales division of Duraplas Industries, we manufacture every tank in-house at our Alstonville factory — the same facility that’s been building poly tanks since 1984. That’s what lets us hold factory-direct pricing across the range.
Underdeck vs Underground: Which Suits Your Property?
Underdeck and underground water tanks solve the same basic problem — getting tank storage off your sightline — but they suit different sites.
An underdeck tank needs an elevated home or deck with clearance underneath. No excavation, no council approval for below-ground works, and a much faster install. An underground tank works on any block, elevated or not, but it needs excavation, a bedding base, and typically a bigger budget.
If your home is already up on stumps or piers, underdeck is usually the simpler and cheaper path to the same result. If you’re on a slab, underground becomes the only out-of-sight option.
Frequently Asked Questions: Underdeck Water Tank Prices
What’s the cheapest underdeck water tank price?
The UD1000 is our entry-level model at $1,150, plus $195 freight. It holds 1,000 litres and suits tight, single-pier gaps under a deck or elevated home.
How much does an underdeck tank cost once freight is included?
Add the flat $195 freight charge to any model’s price. For example, the LUD3000 comes to $2,745 delivered, before plumbing or installation.
Do underdeck tanks need lifting equipment to install?
The two larger models — the LUD3000 and LUD5000 — need lifting equipment on delivery day due to their weight. The UD1000 and UD2000 don’t require it. Check site access with our team before you order.
Can I connect multiple underdeck tanks together?
Yes. The UD1000 and UD2000 are both designed to link together, so you can build extra storage capacity without needing a single larger tank to fit your space.
Is an underdeck tank cheaper than an underground tank?
At the entry level, yes — the UD1000 at $1,150 undercuts the smallest underground model. At the top end, the gap narrows, and your choice comes down to whether your home has clearance underneath or sits on a slab.
Got an elevated home with wasted space underneath it? An underdeck tank could turn that gap into real water storage. Browse the full underdeck range or call 1300 826 532 to talk through which model fits your site.