Small Urban Tanks, Big Impact: Making the Most of Rainwater at Home
- Water Tank Solutions
- 2 days ago
- 7 min read
A small rainwater tank can make a big difference around your home.
You don't need a huge property or a massive water tank to make better use of the rain that falls on your roof.
For many urban homes, a small rainwater tank between 1,000 - 3,000 litres can provide a practical way to capture and store water for the garden, vegetable patch, pots and
other outdoor uses.
The idea is simple:
Capture rain when it falls → store it → use it when you need it.
And with a range of compact and slimline tank designs available, water storage can be a realistic option even where space is limited.
Why consider rainwater storage?
During a good rainfall, thousands of litres of water can run off a roof and disappear down the stormwater system.
At the same time, during a dry spell, we often turn on the tap to water the garden.
A rainwater tank allows you to capture some of that rainfall and save it for later.
For an urban property, stored rainwater can be useful for:
Vegetable gardens
Raised garden beds
Flower beds
Pots and planters
Small lawns
Garden watering
Filling watering cans
Outdoor cleaning
Other suitable non-potable uses
It doesn't have to replace your household water supply to be worthwhile.
Sometimes, the most useful role for a tank is simply to provide a dedicated supply of water for the garden.
How much storage do you actually need?
There's no single answer.
The right tank size depends on:
How much roof area you have available for collection
Your local rainfall
How much water your garden uses
How frequently you want to water
How much space you have available
Whether you're using gravity or a pump
or many urban properties, something in the 1,000–3,000 litre range can be a useful starting point.
A smaller tank takes up less space and can be easier to install.
A larger tank gives you more storage and a bigger buffer during dry periods.
The important thing is to choose the tank around how you intend to use the water, rather than simply buying the biggest tank that will fit.
You don't need a huge backyard
This is where slimline and compact tanks can be particularly useful.
Traditional round tanks can require a significant amount of space.
Slimline tanks can instead be positioned along the side of a house, garage or other suitable area.
For example, the WTS Slimline Tank holds 1,020 litres while measuring only:
750mm wide × 950mm deep × 2,170mm high
That makes it particularly suited to urban properties where available space is at a premium.
Larger compact tanks can provide additional storage where there is room to accommodate them.
The important thing is to consider the available footprint, height, access and how the tank will connect to your roof drainage.
How does a rainwater tank work?
The basic system is surprisingly simple.
Roof → Gutter → Downpipe → Diverter → Tank → Garden
Rain falls onto the roof and flows into the guttering.
The downpipe carries the water down towards the tank.
A suitable rainwater diverter directs water into the tank while allowing excess water to continue through the drainage system when necessary.
The tank stores the water until you need it.
The stored water can then be accessed directly or supplied through a pump, depending on what you want to use it for.
What do you need to install a small urban tank?
A basic installation generally requires:
1. A suitable location
The tank needs to be positioned somewhere that provides adequate space, access and clearance.
Consider:
Height
Width and depth
Access for installation
Connection to your downpipe
Overflow arrangements
Access for future maintenance
If positioning a tank under or near an eave or soffit, make sure there is adequate clearance for the tank and installation.
2. A solid, level base
This is extremely important.
A 1,000 litre tank containing 1,000 litres of water weighs approximately one tonne, before adding the weight of the tank itself.
The tank therefore needs a suitable, stable and level base.
The base should be designed to support the full weight of the tank and water without settling or shifting.
3. A connection from the downpipe
The down pipe needs to be connected to the tank using an appropriate diverter or inlet arrangement.
A good installation should also consider leaves, debris and the first flush of roof runoff.
Keeping the tank and inlet system clean helps maintain better water quality and reduces maintenance.
4. An overflow
Eventually, the tank will fill.
When that happens, excess water needs somewhere to go.
An appropriately sized overflow should therefore be incorporated into the installation and directed to a suitable drainage location.
Do you need a pump?
Not always.
This is one of the advantages of a small rainwater storage system: you can keep it very simple if your intended use doesn't require much pressure.
There are two main approaches.
Option 1:
Gravity-fed – no pump
For simple garden use, you may not need a pump at all.
Water can flow from the tank outlet under gravity and be used for applications such as:
Filling watering cans
Watering nearby garden beds
Connecting a hose for basic garden watering
Other low-pressure outdoor uses
The advantages of a gravity-fed system
Simple: Fewer components means a straightforward installation.
Low maintenance: There's no pump to service.
No pump electricity: You're simply using the natural pressure created by the water level in the tank.
Cost effective: If you don't need pressure, there's no reason to add a pump unnecessarily.
The limitation is pressure.
Gravity-fed water won't generally provide the same pressure as your mains supply.
If you want to run sprinklers or an irrigation system, a pump may be a better option.
Option 2:
Pumped rainwater
Adding a pump gives you considerably more flexibility.
A pump can provide the pressure required for applications such as:
Garden hoses
Drip irrigation
Micro-irrigation
Sprinklers
Multiple garden areas
Larger vegetable gardens
Irrigation systems
The pump should be selected according to the flow and pressure requirements of the system.
A small garden doesn't necessarily need a large pump.
This is where professional advice can be useful: the right pump is the one that delivers what your system actually requires.
Pump or no pump?
A simple way to think about it is:
Your intended use | Likely solution |
Filling watering cans | Gravity-fed |
Watering a few nearby pots | Gravity-fed |
Simple garden hose use | Gravity may be suitable |
Vegetable garden | Gravity or pump |
Drip irrigation | Pump often preferable |
Sprinklers | Pump |
Larger irrigation system | Pump |
Want mains-like pressure | Pump |
There are plenty of situations where no pump is perfectly adequate.
And there are others where adding a small pump transforms a basic storage tank into a useful irrigation water supply.
An example of a suitable pump is the Trevoli Subtron-50 Submersible Pressure Pump-
A light, compact, high-head submersible clean water pump, supplied wired and ready to install — making it a convenient and capable pressure systems suited to this application.
💧 Tip: A pressure tank is highly recommended if being used with dripper line irrigation.
How much rain can your roof collect?
You may be surprised by how quickly a tank can fill.
A useful rule of thumb is:
1mm of rainfall on 1m² of roof = approximately 1 litre of water.
So, for example, 10mm of rain falling on a 100m² roof represents approximately:
1,000 litres of rainfall.
Actual collected water will be affected by factors such as roof area, collection efficiency, losses and the way the system is configured.
But it demonstrates why even a relatively small tank can capture a significant amount of water from an urban roof.
What can you use stored rainwater for?
For many homeowners, the garden is where a small tank really earns its keep.
Vegetable gardens
Consistent watering can be particularly important for vegetables during dry periods.
Having stored water available means you aren't completely reliant on the mains supply.
Pots and planters
Potted plants can dry out quickly, particularly during hot weather.
A nearby tank can make watering easier.
Garden beds
Stored rainwater can provide a convenient supply for flowers, shrubs and other garden plants.
Lawns
If you have a small lawn, stored water can potentially be used for supplementary watering.
Outdoor cleaning
Depending on the application, stored rainwater can also be useful for some outdoor cleaning jobs.
Is rainwater safe to drink?
A tank collecting water from a roof should not automatically be considered a source of drinking water.
Roof surfaces, gutters and surrounding areas can introduce contaminants into collected rainwater.
If rainwater is intended for potable use, the system needs to be specifically designed, treated and maintained for that purpose.
For a simple urban tank used for garden watering and other suitable non-potable applications, this isn't usually the objective.
The focus is simply on capturing useful rainwater and putting it to work around your property.
Preparing for summer
One of the best times to think about water storage is before you need it.
Once the garden is already dry and the forecast is showing a prolonged period without rain, it's too late to capture the rainfall that has already passed.
Installing a small tank means you can capture water during wetter periods and have it available when the garden needs it.
And because urban tanks can be relatively compact, you don't necessarily need to sacrifice a large part of your garden to make it happen.
Small tank. Big difference.
Rainwater storage doesn't have to mean installing a huge tank and completely changing your property.
For an urban home, a compact tank can provide a practical middle ground.
You can capture rainwater from your roof, store it on your property and use it for the things that make sense.
1,000 litres. 2,000 litres. 3,000 litres.
The right size depends on your space, your roof and what you're trying to achieve.
And when it comes to getting water from the tank to your garden, you can choose between a simple gravity-fed setup or a pumped system depending on the pressure you need.
At WTS, we can help you work through the options and find a water storage solution that suits your property and how you want to use it.
Make the most of the rain that falls on your roof.
Small tank. Small footprint. Big difference.
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