How to Set Up a Rain Harvesting™ System

Ask most people what they need to harvest rainwater and they’ll give you three answers: a roof, a tank, and some rain. It’s a perfectly reasonable assumption, and it’s also the most common reason rainwater tanks underperform.

A rainwater tank is a storage vessel. A system is everything that works around it to keep water moving in, contaminants out, and water ready to use. Get the system right and you’ll be rewarded with cleaner water, more of it, and far less maintenance over the life of your tank.

At Rain Harvesting™, we’ve spent more than twenty-five years refining what that system should look like. The result is a defined methodology we call the Rain Harvesting™ System: twelve steps that take water from the roof to the tap, with a purpose-built product solving the job at each stage.

This guide walks you through what a Rain Harvesting™ System is, why each step earns its place, and how to set one up on your property.

Why a Tank on Its Own Isn’t Enough

How much you actually get out of a rainwater setup depends on much more than the tank you choose. The more thoroughly water is filtered, diverted, screened, and secured before it reaches storage, the better the water you end up with: ready to use, with less ongoing maintenance and a longer-lasting setup.

What makes the difference isn’t the tank. It’s the system wrapped around it.

A well-designed Rain Harvesting™ System delivers four clear benefits:

• Better water quality, because contaminants are removed in stages before water reaches storage
• Higher yields, because less water is lost to blocked gutters and overflow events
• Lower maintenance, because sediment, leaves, and insects are stopped at the source rather than cleaned out of the tank
• A longer-lasting setup, because better water quality means less wear on pumps, filters, and appliances

That philosophy of progressive, stage-by-stage contaminant reduction is what every Rain Harvesting™ product is built to support, and what every step of the Rain Harvesting™ System is designed to deliver.

The Rain Harvesting™ System: 12 Steps from Roof to Tap

A complete Rain Harvesting™ System is built from twelve clear steps, each addressing a specific need. Follow them in order and you end up with a setup that consistently delivers the four benefits above.

Step 1: Understand Your Rainwater Needs

Calculate how much rainwater you need and how you’re going to use it, and determine the average rainfall in your environment. Are you topping up a garden, running a laundry and toilets, supplying the whole home, or going fully off-mains? Each level of use brings a different expectation for volume, pressure, and water quality.

A simple calculation gives you a useful starting point: roof catchment area in square metres, multiplied by annual rainfall in millimetres, gives you roughly the litres of rainwater your roof will shed in a typical year. The Bureau of Meteorology provides reliable rainfall data for your postcode.

Step 2: Store Your Rainwater

Choose the storage vessel that has the volume for your needs, and decide on the best location based on proximity to your collection area and any inhibiting factors. Tank size should match your intended use, your roof catchment, and your longest expected dry period. Slimline tanks fit narrow side yards; wider squat tanks suit open ground; below-ground tanks free up surface space.

Step 3: Assess Your Rainwater Collection Area

Audit and prepare your property, factoring in roof surface materials, overhanging trees and vegetation, gutters, and any flaking paint. Replace any hazardous building materials, control pests, and install gutter mesh to minimise blockages.

This is where Blue Mountain Gutter Mesh, our brand of gutter protection, earns its place. It keeps leaves and debris out of gutters and downpipes, prevents blockages during heavy rainfall events, and dramatically reduces how often you need to clean anything downstream.

Step 4: Clean Your Rainwater: Filter Leaves and Debris

Keep larger pieces of matter like leaves and debris out of your system by installing rain heads on every downpipe. Our Leaf Eater range deflects leaves and debris while keeping mosquitoes out of pipes that hold standing water. The Leaf Eater Advanced is compact and fits tight spaces with a swivelling base for vertical or horizontal mounting; Leaf Eater Original and Leaf Eater Slimline offer alternatives to match different architectural styles and flow requirements.

For exceptional inlet quality, our Maelstrom Filter combines super-fine 180 micron filtration (five times finer than a standard tank screen) and can be installed on-tank, pre-tank, on a wall, or in a pit.

Step 5: Clean Your Rainwater: Divert the First Flush of Rainwater

Keep smaller pieces of fine sediment and dissolved solids out of your system by installing a First Flush Diverter. The first run of rainwater off your roof carries the highest concentration of dust, pollen, and contaminants built up between rain events, and a diverter sends that initial water away from the tank so cleaner water flows in behind it.

We make several configurations to suit your system:

• First Flush Downpipe for simple, compact installations on individual downpipes
• First Flush Delta for higher volume diversion where wall or post mounting suits
• First Flush In-Ground allows wet systems to effectively function as dry systems

If you’d rather combine rain head and first flush functions in a single unit, our Total Rain and Clean Rain ranges deliver both stages in one product.

Step 6: Secure Your Rainwater System

Keep animals, insects, and sunlight out, and prevent stormwater and groundwater backflow. Our Tank Screen 360 sits at the tank inlet to keep mosquitoes, insects, and debris out, with easy-clean access for ongoing maintenance. Mozzie Stoppa flap valves fit to the ends of all pipes running from the tank and to overflow outlets, to keep insects out.

To prevent backflow at the overflow outlet, install an Air Gap between the overflow pipe and the stormwater main.

Step 7: Decide on a Pump or Gravity-Fed System

Research and talk to specialists to find the ideal way to draw water from your tank. Select a pump sized for your application, whether that’s garden irrigation, toilet flushing, or whole-of-home supply. Consider whether a gravity-fed setup is feasible for your site (typically when the tank sits well above the point of use).

For better draw quality, fit a Floating Off-Take Valve inside the tank. It draws water from just below the surface, where the cleanest water naturally sits, rather than from the sediment at the base. A small upgrade that noticeably improves water quality at the tap.

Step 8: Manage Standing Water

For wet systems where pipes hold water between events, regularly draining those pipes prevents anaerobic fermentation. Our Wet/Dry Valve automatically drains charged lines after it rains, with an electronic auto-release timer that lets you set drainage frequency, and a larger drain size that minimises clogging risk.

Sliding Gate Valves offer manual shut-off at the downpipe for isolating parts of the system (useful during cleaning), and our 3-Way Water Diverter allows easy manual diversion in non-pressurised systems for routing water between the tank and the garden.

Block sunlight with a Solar Shield at the inlet area to help prevent algae growth.

Step 9: Final Stage Rainwater Filtration

Decide how much filtration your tank water needs based on how you’re using it.

Step 10: Optimise Your Overflow

Overflow isn’t a failure of the system, it’s part of the design. Make sure if you’re plumbed into a stormwater main that you’re using an Air Gap to prevent backflow, and that your outlet is equal to or larger than the inlet to handle peak flow events. Direct excess water somewhere useful rather than letting it pool at the tank base.

Step 11: Monitor Your Water Level

Keep track of your tank levels, inflows, and outflows. You can’t manage what you can’t measure!

Our Tank Gauges lets you see at a glance how much water you have. Remote monitoring models display the reading on your phone, which makes it much easier to plan usage through drier periods and avoid surprise empty tanks. Keep a record of your data over time to spot trends and predict shortfalls before they happen.

Step 12: Care for Your System

A Rain Harvesting™ System is low-maintenance, but not no-maintenance. Regularly check for leaks, holes where pests can enter, or build-up of contaminants. Five minutes of routine inspection every few months keeps the whole system performing for decades.

The Bottom Line

A rainwater tank is a great investment. A complete Rain Harvesting™ System is what makes that investment pay off, in water quality, in volume, and in how much work the system needs year to year.

If you’re planning a new setup, the 12 Rain Harvesting™ Steps above are the framework. If you’re optimising an existing one, the same list makes it easy to spot the gaps.

Your local Irrigear store can help you spec a Rain Harvesting™ System for your property and your intended water use, whether that’s keeping the garden green, supplementing household supply, or running a completely off-mains property.

Cleaner water. Lots of it. That’s what a Rain Harvesting™ System delivers.

Rain Harvesting™ has been designing purpose-built rainwater harvesting products for over twenty-five years, with systems installed in more than thirty countries. The 12 Rain Harvesting™ Steps are the foundation of every Rain Harvesting™ System we design. Explore the range at your local Irrigear store.