Underground water tank prices at The Water Tank Factory start at $2,895. That’s for the 3,000-litre LU3000 under yard model. Prices run to $4,495 for the 5,000-litre LU5000 under driveway model, with three other configurations in between. The right model depends on where the tank needs to sit — under a lawn, or under a trafficable driveway.
Underground tanks solve a problem round and slimline tanks can’t. What happens when there’s no open ground space left, and no side passage narrow enough to help either? Here’s exactly what each model costs, what you get for it, and how to pick between them.
Underground Water Tank Price List
All four models are Duraplas Lattice™ Underground Water Tanks. They share the same patented low-profile design — we’ve simply sized and specced each one differently depending on capacity and what sits on top of it. Standard area freight costs $325 per tank. Every model needs lifting equipment at delivery, so factor that into your install planning from the start — don’t leave it as a surprise on the day.
Why Driveway Models Cost More
The price jump from yard to driveway model isn’t a margin decision. It’s $530 more on the LU3000 and $600 more on the LU5000. Driveway models are trafficable — engineers build them to handle a vehicle parked or driven over them once you install them correctly. That extra capability sits built into the tank itself.
Driveway models include a heavy-duty galvanised lid and ring riser as standard. Yard models skip this hardware, since nothing heavier than foot traffic ever sits above them. If you’re planning to park a car, or if the tank’s manhole will sit anywhere near a driveway surface, the driveway model isn’t an upsell. It’s the only version built for that load.
LU3000 vs LU5000: Which Capacity Suits Your Block?
Both models use the same lattice design. We’ve simply scaled it up for the LU5000.
LU3000 — Nominal dimensions of 2,420mm width by 2,520mm length by 900mm height, with a 250kg shot weight. This is the tighter footprint of the two. It suits smaller blocks, or properties where 3,000 litres genuinely covers what you need.
LU5000 — Nominal dimensions of 2,780mm width by 3,500mm length by 950mm height, with a 325kg shot weight. This one needs a meaningfully larger footprint underground, but delivers real extra capacity — we see it go into new unit developments and larger homes most often.
If your excavation area can fit the larger footprint, the LU5000 gives you close to 70% more capacity for roughly 35–40% more cost, depending on which yard/driveway pairing you’re comparing. That’s a reasonable trade-off if your household or property genuinely needs the extra storage.
Where Underground Tanks Make Sense
Underground tanks are usually the third option people land on, not the first. A round tank often needs more open space than the block has. A slimline tank still can’t fit neatly beside the house, shed or fence line. That’s not a downside — it’s exactly the gap underground tanks fill.
They suit small urban blocks, new home builds, renovations, and any property where the tank needs to stay completely out of sight. In exchange, you take on excavation and lifting equipment at install, instead of a straightforward above-ground placement.
The patented lattice design keeps the tank low-profile, which helps reduce excavation depth compared to older, deeper underground tank designs. That matters both for install cost and site suitability. Not every block has room to dig deep.
What About Sloping Sites?
If your excavation sits at the deep end of a sloping site, you’ll likely need a manhole extension riser. This cut-to-length, flexible accessory adjusts the manhole height to the correct angle. It costs $250, and we strongly recommend ordering it with the tank — couriers struggle to freight it on its own once your main order has shipped.
Check the maximum depth allowance in the installation guide before you order. Factor the riser into your budget upfront if your site has any real slope to it. Better that than discovering the need for it mid-excavation.
Warranty on Underground Tanks
Underground tanks carry a 5-year warranty across the full range — different from the 20-year warranty on our round and slimline poly tank models. That difference comes down to the application. Underground tanks operate in a different environment entirely: buried, and for driveway models, load-bearing. The warranty structure reflects that.
Frequently Asked Questions: Underground Water Tank Prices
What’s the actual price difference between the LU3000 and LU5000?
Comparing yard models: $2,895 for the LU3000 versus $3,895 for the LU5000 — a $1,000 difference for 2,000 extra litres of capacity. The two driveway models show a similar gap, at $3,425 versus $4,495.
Do I need the driveway model if I’m only parking a car occasionally?
Yes. If there’s any chance a vehicle will drive over or park on the installed tank, choose the trafficable driveway model. Engineers build it specifically for that load — the yard model can’t handle it.
Is delivery included in the price?
No. Standard area freight costs $325 per tank, and delivery requires lifting equipment. Confirm your delivery area and access before you order, since underground tanks need proper equipment to place safely.
Do I need the manhole extension riser?
Only if your site slopes and the tank’s manhole sits at the deep end of the excavation. Order this $250 accessory with the tank itself — couriers find it difficult to freight separately.
How does underground tank pricing compare to round or slimline tanks?
Underground tanks generally cost more per litre than round or slimline models. That reflects the specialised design, the trafficable engineering on driveway models, and the installation requirements. For a full price comparison across the range, see our 2026 water tank price guide.
Get the Right Underground Tank for Your Block
Whether you need the compact LU3000 or the higher-capacity LU5000, in a yard or trafficable driveway configuration, The Water Tank Factory supplies the full Duraplas Lattice™ Underground Tank range factory-direct from Alstonville, Northern Rivers NSW — Australian family-owned since 1984. Call our team on 1300 826 532 or visit watertankfactory.com.au to talk through excavation, freight and which model suits your site.