Slimline water tank prices at The Water Tank Factory start at $825. That’s for the 450-litre SL450. Prices run to $2,450 for the 5,000-litre ML5000SQ, with nine other models in between. The right choice comes down to one measurement more than any other — the width of the space you’re fitting it into. Here’s the full breakdown.
| Model | Capacity | Width | Price | Freight |
|---|---|---|---|---|
| SL450 | 450L | 600mm | $825 | $195 |
| SL650SQ | 650L | 600mm | $925 | $195 |
| SL1180UR | 1,180L | 600mm | $1,275 | $195 |
| SL2000UR | 2,000L | 625mm | $1,295 | $195 |
| SL1650SQ | 1,650L | 700mm | $1,395 | $195 |
| SL3000UR | 3,000L | 700mm | $1,395 | $195 |
| SL3000SQ | 3,000L | 760mm | $1,895 | $195 |
| SL4000UR | 4,000L | 920mm | $2,050 | $195 |
| SL4000SQ | 4,000L | 955mm | $2,250 | $195 |
| SL5000UR | 5,000L | 940mm | $2,095 | $195 |
| ML5000SQ | 5,000L | 1,160mm | $2,450 | $195 |
Freight is a flat $195 across the entire range for standard delivery areas.
Built for Units, Duplexes and Tight Urban Blocks
Round water tanks suit open rural and semi-rural properties with room to spare beside a house or shed. Slimline water tanks solve a different problem entirely — they’re built for sites where that open space simply doesn’t exist.
The SL2000UR is a common choice for units and duplexes, where a narrow side strip is often the only spot available for water storage. That pattern holds across our slimline customer base more broadly — this range does the most work in cities and inner-suburban areas, from Sydney and Brisbane through to the Gold Coast, Newcastle, the Central Coast and Canberra, where side passages and boundary lines are the norm rather than the exception.
If you’re on a rural block with open access, a round water tank will usually give you more capacity for your budget. Slimline earns its place when space, not price, is the deciding factor.
How Narrow Can You Go? A Width-First Buying Guide
With slimline tanks, width is the spec that actually determines whether a tank fits — capacity is secondary. Here’s how the range breaks down by footprint.
600mm wide (SL450, SL650SQ, SL1180UR): the narrowest tier in the range, and the one that fits genuinely tight side passages — think the gap beside a garage or between a fence and a wall. Capacity tops out at 1,180 litres at this width, so these suit drinking water, backup supply or small-scale garden use rather than whole-house storage.
625–700mm wide (SL2000UR, SL1650SQ, SL3000UR): still narrow enough for most side-passage installs, but with meaningfully more capacity — up to 3,000 litres. This tier covers the sweet spot for units, duplexes and townhouses needing a genuine household supplement.
760–955mm wide (SL3000SQ, SL4000UR, SL4000SQ): a step wider, needed to unlock 3,000 to 4,000 litres in a squat or upright profile. Worth measuring carefully — the jump from 700mm to 760mm can matter on a truly tight block.
940mm and above (SL5000UR, ML5000SQ): the widest tier the slimline family reaches, needed to hit 5,000 litres. If your space allows this width, it’s worth comparing directly against the round range too, since the price gap narrows at this capacity.
Measure your actual install space before you shop by capacity — on a narrow block, width rules out options before price ever enters the conversation.
Slimline vs Midline: When Extra Width Buys You More Capacity
At 5,000 litres, the range offers two distinct shapes, and the difference comes down to a 220mm width trade-off.
The SL5000UR holds the line at 940mm wide, standing 2,170mm tall to make up the difference. It’s the tank to choose when your side passage is genuinely tight and you can’t spare the extra width.
The ML5000SQ — our midline model — trades that narrow footprint for 1,160mm of width and a lower, squatter 1,850mm profile. It costs $355 more, but it’s a noticeably easier tank to work around: lower inlet height, less climbing for maintenance, and a shape that reads less like a “slimline squeeze” and more like a compact standard tank.
If you’ve measured your space and have 1,160mm to spare, the midline is worth the extra spend for the easier access. If you’re working right at the edge of what fits, the SL5000UR is what makes 5,000 litres possible at all.
What’s Included in Slimline Tater tank Prices
Every price above covers the tank itself, manufactured at our Alstonville factory using computerised manufacturing techniques for consistent wall strength. Freight is a separate flat $195 charge across the range.
A few things sit outside the tank price:
- Delivery assistance — smaller models need one person to assist our driver. That scales with size: the SL2000UR through SL4000SQ need two people, and the SL5000UR and ML5000SQ need three.
- Plumbing and installation — connecting the tank to your roof catchment and household plumbing is a separate job, usually handled by a licensed plumber.
- Stands — some smaller models suit a galvanised stand for elevated positioning; check the product page for your chosen model.
Worth noting: slimline water tanks generally cost more per litre than round water tanks at equivalent capacities — roughly $1.83 per litre for the smallest SL450 down to $0.42 per litre for the SL5000UR, against a comparable round tank’s lower per-litre cost. That’s the price of the narrow footprint, not a reflection of quality — every slimline water tank in the range carries the same 20-year warranty (10+10) and complies with Product Certification to AS/NZS 4766.
Frequently Asked Questions: Slimline Water Tank Prices
What’s the cheapest slimline water tank price?
The SL450 is our entry-level model at $825, plus $195 freight. It holds 450 litres in a 600mm-wide footprint, suited to patios, caravans or mobile homes.
What’s the difference between a slimline and a midline water tank?
Slimline tanks run narrower — as tight as 600mm wide — trading footprint for height. Midline tanks like the ML5000SQ sit wider (1,160mm) but lower and squatter, offering easier access where you have slightly more space to spare.
Are slimline water tanks suited to units and duplexes?
Yes. Models like the SL2000UR are specifically popular in unit and duplex settings, where a narrow side strip is often the only available space for water storage.
What’s the narrowest slimline water tank available?
Three models share the narrowest 600mm footprint — the SL450, SL650SQ and SL1180UR — suited to genuinely tight side passages, with capacity up to 1,180 litres.
Do larger slimline tanks need extra help for delivery?
Yes. The SL5000UR and ML5000SQ both need three people to assist our delivery driver, up from one person for the smaller models in the range.
Not sure which width fits your block? Browse the full slimline water tank range or call 1300 826 532 to talk through sizing for your property.