If you need reliable rainwater storage but do not have enough room for a large round tank, slimline water tanks NZ offer a practical way to collect and store rainwater without taking over your outdoor space.

Designed to fit neatly alongside homes, garages, fences and other narrow areas, slimline tanks make it easier for New Zealand homeowners to add rainwater storage where space is limited. They can be used for garden watering, outdoor cleaning and other suitable applications, while appropriately designed and treated systems can provide additional household water options.

At Just Tanks, our slimline range includes Devan stormPANEL and stormBANK water tanks, with options from 1,000 litres through to larger modular storage solutions. The tanks are made from UV-stabilised polyethylene and are available in multiple colours to suit different properties.

The key is choosing a tank that works with your available space, roof catchment, water requirements and installation conditions.

Why Slimline Water Tanks Are a Smart Choice for New Zealand Homes

Traditional round tanks can provide excellent storage, but they are not always easy to accommodate on an urban property. A narrow side passage may have enough room for a slimline tank while being too restricted for a large circular tank.

That is where a slimline rainwater tank can make a real difference.

A well-positioned tank can turn an otherwise unused area beside a house or garage into useful water storage. Instead of sacrificing a large section of your garden, you can make use of vertical and narrow spaces.

Make better use of limited outdoor space Slimline Water Tanks

Space is often the biggest reason homeowners look at slimline water storage.

A slimline tank can be positioned alongside a building, fence or other suitable location, allowing you to collect rainwater while keeping more of your usable outdoor area available.

Just Tanks’ stormPANEL and stormBANK ranges are specifically designed around this type of space-efficient installation.

Add rainwater storage without a large round tank

Slimline tanks are not simply smaller versions of traditional tanks. Their shape is designed around properties where width and footprint matter.

This makes them particularly useful for Slimline Water Tanks :

• Urban homes
• Townhouses
• Properties with narrow side access
• Homes with limited garden space
• Garages and workshops
• Commercial buildings
• Properties where appearance is an important consideration

Use collected rainwater around your property

A properly connected rainwater harvesting system can provide stored water for a range of practical uses.

Depending on the system, homeowners may use harvested rainwater for:

• Garden irrigation
• Washing vehicles
• Outdoor cleaning
• Garden maintenance
• Emergency water storage
• Other suitable non-potable applications

Just Tanks recommends adding a pump and hose connection where required to make stored water easier to use around the property.

How Slimline Rainwater Tanks Work

The basic idea behind a slimline rainwater harvesting system is simple.

Rain falls onto your roof and flows into the guttering system. From there, a suitable connection directs the water through the downpipe and into the storage tank.

Once the water is stored, it can be accessed through the appropriate outlet, pump or connection depending on how your system has been designed.

Your roof is the starting point for Slimline Water Tanks collection

Before buying a tank, look at the roof area available for collection.

A tank can only store water that your roof and rainfall conditions can provide. A larger tank may offer more storage capacity, but the available catchment area still matters.

This is why tank selection should consider more than just litres.

The downpipe location matters too

A tank positioned close to a suitable downpipe can make installation much simpler.

Before choosing a location, check:

• Where your downpipes are located
• Whether the tank can sit on suitable ground
• How the inlet pipe will be connected
• Where overflow will go
• Whether there is enough room around the tank
• How the stored water will be accessed

Planning these details early can prevent expensive changes later.

Choosing the Right Slimline Water Tank Size

One of the most common questions homeowners ask is, ‘What size slimline water tank do I need?

There is no single answer for every property.

The right capacity depends on your available space, roof catchment, expected water use and how much reserve you want to keep.

1,000 litre slimline water tanks

A 1,000L tank can be useful when space is particularly restricted or when the main objective is to collect a smaller amount of rainwater for outdoor use.

It can also be a useful starting point for homeowners who want to introduce rainwater harvesting without committing a large part of their property to storage.

2,000 litre slimline water tanks

A 2,000L system provides additional storage while still keeping the space-saving benefits of a slimline design.

Just Tanks’ stormPANEL range is available in 1,000L and 2,000L configurations.

Larger slimline water storage systems

If you need more storage but do not have space for one large tank, modular arrangements can provide another option.

The stormBANK range is available from 1,000L, with larger configurations and the ability to connect multiple tanks to increase overall storage.

This can be useful when your water-storage requirements may grow over time.

StormPANEL vs StormBANK: Which Slimline Tank Is Right for You?

Just Tanks offers two key slimline solutions: stormPANEL and stormBANK.

Both are designed to provide space-efficient rainwater storage, but their shapes and configurations are different.

stormPANEL for narrow spaces beside your home

The Devan stormPANEL is a flat-profile slimline tank designed to fit neatly into narrow areas.

It is available in 1,000L and 2,000L sizes and can be connected with additional tanks where greater storage is required.

This makes stormPANEL particularly worth considering if your available space is long and narrow.

stormBANK for flexible modular storage

The stormBANK provides a compact cylindrical design while maintaining a space-efficient footprint.

Just Tanks offers stormBANK options from 1,000L, with larger storage configurations up to 5,000L and the ability to connect multiple tanks where required.

This flexibility can be useful when you want to build a larger rainwater storage system without relying on one very large tank.

Which one should you choose?

The better option depends on your property rather than simply choosing the tank with the highest capacity.

Consider:

• Available width and depth
• Tank height
• Position of your downpipe
• Required water capacity
• Access for installation
• Appearance
• Future storage requirements

If you are unsure, a site assessment can help determine which configuration makes the most sense.

What Are Slimline Water Tanks Made From?

The Just Tanks slimline range uses UV-stabilised polyethylene, a material designed for durable outdoor water storage. The tanks are resistant to rust and corrosion and are designed for long-term outdoor use.

This can be particularly useful for properties where the tank will be exposed to changing weather conditions.

Why polyethylene is useful for water storage

Compared with materials that can rust or corrode, polyethylene provides a practical option for above-ground water storage.

The Just Tanks range is also available in 11 colour options, allowing homeowners to choose a tank that works with their property’s exterior.

For a visible tank installation, colour can make a surprisingly large difference to the finished appearance.

Where Can Slimline Water Tanks Be Installed?

Slimline tanks are designed for above-ground installation on an appropriate flat, level surface.

Potential locations include:

• Beside a house
• Alongside a garage
• Next to a suitable fence
• Under appropriate eaves
• Along a narrow side passage
• Near a suitable downpipe

The exact location should always be checked against the tank manufacturer’s installation requirements and the conditions of the site.

The tank needs a proper base

A full water tank is extremely heavy, so the base is not something to compromise on.

Just Tanks recommends a level installation surface and states that a 100 mm reinforced concrete slab is preferred for suitable sites. It also identifies paving slabs over a firm, well-compacted sand and gravel base as an alternative where the relevant ground conditions are met.

The correct installation method should be confirmed for your particular property and tank.

Leave room for connections and maintenance

Don’t measure the space based only on the tank dimensions.

You also need to think about:

• Inlet connections
• Outlet connections
• Overflow
• Pump connections
• Downpipe access
• Maintenance
• Future servicing

A tank that technically fits into a gap may still be difficult to install or maintain if there is no working room around it.

Slimline Water Tanks for Auckland and Urban NZ Properties

Slimline tanks are particularly relevant to urban properties where outdoor space is limited.

In areas with compact sections, a large round tank may compete with gardens, driveways, entertaining areas or accessways.

A slimline configuration can make better use of narrow areas that might otherwise remain unused.

Just Tanks positions its range around urban rainwater harvesting, supplying and installing slimline tanks for New Zealand properties.

A practical example

Imagine a home with a narrow side passage between the house and boundary.

There is enough length for a tank, but not enough width for a traditional large round tank.

A slimline tank can potentially use that narrow space while connecting to a nearby downpipe. The homeowner can then collect roof runoff and use the stored water for suitable outdoor applications.

The important part is planning the complete system rather than choosing the tank first.

DIY Slimline Water Tank Installation or Professional Installation?

One advantage of the Just Tanks range is that homeowners can choose between DIY options and professional installation.

When DIY installation may make sense

A competent homeowner or experienced handyperson may prefer a DIY installation for a straightforward retrofit, such as connecting a tank for garden irrigation or vehicle washing.

Just Tanks offers a Quickfit DIY Kit designed to simplify rainwater collection from suitable round downpipes. The kit includes the downpipe diverter, diverter hose kit and hose fitting.

When professional installation is the better option

Professional installation can be preferable when:

• The system connects into household plumbing
• You need a pump system
• The installation is technically complicated
• The site has access or ground challenges
• You want the complete system supplied and installed
• Plumbing or other regulated work is involved

Just Tanks offers fully installed rainwater harvesting systems and can arrange a site assessment to recommend a solution based on the property and water requirements.

Slimline Water Tank Installation: What Should You Plan First?

A successful installation starts before the tank arrives.

Measure the available area

Measure the actual installation space, including the width, depth and height available.

Then compare those measurements with the manufacturer’s tank dimensions.

Identify the best downpipe

Look for the downpipe that provides the most practical connection to the tank.

A nearby downpipe can reduce unnecessary pipe runs and make the system cleaner.

Prepare the base

The base must be level and capable of supporting the filled tank.

Do not place a full water tank on an unsuitable or unstable surface.

Plan overflow

Overflow should be considered as part of the original design.

Water needs a safe and appropriate path away from the tank and surrounding structures.

Decide how you will use the stored water

Your intended use affects the type of pump, fittings and filtration you may need.

A simple garden irrigation system has different requirements from a more comprehensive household rainwater system.

Can Slimline Water Tanks Provide Drinking Water?

A rainwater tank and a potable water system are not automatically the same thing.

If you want to use harvested rainwater for drinking or other potable purposes, the water collection, storage, filtration, treatment and plumbing system must be appropriately designed.

Just Tanks offers UV filtration and complete rainwater harvesting solutions for homeowners looking for a more comprehensive backup water system.

Why filtration matters

Rainwater collected from a roof can contain contaminants from the roof surface, gutters and surrounding environment.

For potable applications, appropriate filtration and treatment should therefore be considered as part of the complete system rather than added as an afterthought.

If you are looking for a household backup supply, speak with a qualified professional about the complete water treatment and plumbing requirements for your property.

Common Mistakes to Avoid When Buying Slimline Water Tanks

Buying a water tank is not just about finding the lowest price or the biggest capacity.

A few simple mistakes can make an otherwise good tank unsuitable for your property.

Choosing capacity before measuring the space

Always measure first.

A tank may have the capacity you want but still be unsuitable for the available area.

Forgetting the downpipe location

A perfect tank location is not much use if connecting it to the roof drainage system becomes unnecessarily complicated.

Look at the gutter and downpipe layout before deciding where the tank will go.

Ignoring the base

A filled tank places substantial weight on its supporting surface.

Follow the manufacturer’s installation requirements and make sure the base is properly prepared.

Buying more storage than you can realistically use

More capacity is not always better.

Think about your actual water demand and how much rainfall your roof can collect.

Treating appearance as an afterthought

If the tank will be visible from your living areas, driveway or street, consider the colour and shape before purchasing.

Just Tanks offers its stormPANEL and stormBANK tanks in 11 colours, giving homeowners more flexibility when matching the tank to their property.

How to Get More Value From Your Slimline Water Tanks

Once your tank is installed, a few simple habits can help you make better use of your stored water.

Keep gutters and collection areas maintained

Leaves and debris can enter the rainwater collection system and affect water quality and tank performance.

Regular gutter maintenance is a simple part of looking after the whole system.

Check connections regularly

Inspect visible fittings, hoses, outlets and connections from time to time.

If you notice leaks or damaged components, address them before they become a larger problem.

Use a suitable pump where required

A pump can make stored rainwater much easier to use for garden irrigation, outdoor cleaning and other applications where pressure is needed.

Think about future water needs

If you may expand your garden or increase your water use, consider a system that can be expanded.

The modular nature of some slimline configurations allows additional storage to be connected where appropriate.

Slimline vs Round Water Tanks: Which Is Better?

There is no universal winner.

The better tank shape depends on your property.

Choose a slimline tank when space is limited. Slimline Water Tanks

Slimline tanks are a strong choice when you have a narrow installation area and want to keep your garden or outdoor space open.

They are particularly suited to urban properties where the tank needs to work around existing buildings and boundaries.

Consider a round tank when you have more open space

A round tank may make more sense when you have plenty of available land and want to prioritise larger storage capacity.

The decision should come down to the available space, required capacity and overall purpose of the system.

For a more detailed comparison, see our guide to [slimline vs round water tanks].

Why Choose Just Tanks for Slimline Water Tanks NZ?

Choosing a water tank is only one part of the process.

You also need to consider delivery, installation, plumbing, filtration and how the system will actually work on your property.

Just Tanks focuses on urban rainwater harvesting and supplies, delivers and installs slimline water tanks across New Zealand. The company offers both DIY and professionally installed options, allowing homeowners to choose an approach that suits their project.

The current range includes Slimline Water Tanks :

• Devan stormPANEL slimline tanks
• Devan stormBANK tanks
• Slimline DIY solutions
• Quickfit DIY installation kits
• Fully installed rainwater harvesting systems
• UV filtration options
• Pump and water-use solutions

For customers who are unsure what configuration suits their property, Just Tanks also offers a free site visit for its installed solutions.

Final Thoughts:

If outdoor space is limited, a Slimline water tank NZ solution can give you a practical way to start harvesting rainwater without sacrificing a large part of your garden or driveway.

The best choice is not simply the tank with the largest capacity. Start by looking at your available space, roof catchment, downpipe position and intended water use. Then consider the tank shape, capacity, base, pump, filtration and installation method.

For homeowners who want a straightforward DIY setup, Just Tanks offers slimline tanks and Quickfit options. For a complete system, professional installation and filtration are also available.

If you are comparing slimline water tanks in NZ, explore the Just Tanks range or request a free site assessment to find a solution that fits your property and water requirements.

Frequently Asked Questions

What are slimline water tanks used for?

Slimline water tanks are used to store rainwater where available ground space is limited. Depending on the system, stored water can be used for garden irrigation, vehicle washing, outdoor cleaning, emergency storage and other suitable applications.

What size slimline water tank should I buy?

The right size depends on your available space, roof catchment, intended water use and required storage. Just Tanks offers slimline options from 1,000 litres, with larger modular configurations available.

Are slimline tanks suitable for small sections?

Yes. Their narrow design makes them particularly useful for properties where a traditional round tank would take up too much usable space.

What is the difference between stormPANEL and stormBANK?

stormPANEL uses a flat-profile slimline design and is available in 1,000L and 2,000L options. stormBANK uses a compact cylindrical design and is available in configurations from 1,000L, with larger modular storage options.

Can I install a slimline water tank myself?

For suitable straightforward installations, a competent DIY homeowner may be able to install a slimline tank. Just Tanks also offers DIY kits designed to make suitable installations easier. For plumbing connections, more complex systems or regulated work, professional installation may be appropriate.

Can I connect multiple Slimline Water Tanks together?

Yes, some Just Tanks slimline configurations can be connected to increase overall storage capacity. This provides a flexible option when a single larger tank is not suitable for the property. Slimline Water Tanks.

Are slimline water tanks durable?

Just Tanks’ stormPANEL and stormBANK tanks are made from UV-stabilised polyethylene and are designed for outdoor water storage. They are also resistant to rust and corrosion.

How long do Just Tanks slimline tanks last?

The applicable manufacturer’s warranty depends on the tank model. Just Tanks currently states a 10-year domestic warranty for stormPANEL and a 20-year domestic warranty for stormBANK.