16 Apr Rainwater Harvesting for Perth Homes: Systems That Work in Our Climate
Let’s face it, water in Perth isn’t something folks can just take for granted these days.
We have spent nearly forty years working in gardens around Perth. We have seen water restrictions come and go (and return again).
Lawns allowed to turn brown through a scorching summer. Homeowners weeping over dead plants that cost fortunes to install.
Somewhere along the way, rainwater harvesting moved from being a “nice to have” to something that makes actual financial sense.
If you are considering the installation of rainwater tanks in Perth, you clearly belong to the progressive thinkers. However, this is an important fact to note—most systems of rainwater harvesting do not function in exactly a duplicate manner in our climatic conditions.
What works steadily and constantly under Sydney’s constant rainfall probably leaves you yearning during the dry months for all that water supposed to be saved.
Why Perth’s Climate Makes Rainwater Harvesting Tricky (But Worth It)
Perth gets most of its rain between May and September. That’s your window. Come December? You’ll be lucky to see a drop.
Bureau of Meteorology climate data confirms Perth receives around 730 mm of annual rainfall, with approximately 77% falling during the cooler months. This seasonal concentration means your rainwater harvesting Perth system needs to think differently.
You’re not collecting water all year round like they do over east. You’re basically trying to make it through the summer, stockpiling in winter.
An average Perth home can collect about 140,000 litres off a 200-square-metre roof per year. Sounds like a lot until you work out how much your garden drinks in per week over peak summer months.
Tank Size Matters More Than You Think
People buy a 2,000-litre slimline tank because it fits nicely against the fence and looks tidy. Then wonder why they run out of water by January. For water-wise gardening in Perth homes to actually work, you need storage that reflects reality.
Our general recommendations are based on years of Perth installations:
- Garden use only: minimum 5,000 litres. This gives you enough buffer to get through those long dry spells without your plants suffering.
- Toilets and laundry included: You’re looking at 10,000 litres minimum, preferably more. The extra household use adds up faster than you’d think.
- Large established gardens: Consider 15,000+ litres if you’ve got a significant lawn area or water-hungry plantings. Yes, it’s an investment. But spreading your usage across the dry months without running empty is the whole point.
During our landscape design consultations, we map out exactly how much water your specific garden will need. Native plants? You’ll get away with less. Established lawn and exotic species? Better size up.
There’s no point installing a rainwater system that can’t actually support what you’re growing. We’ve just seen too many disappointed homeowners who went too small and regretted it by their first summer.
First Flush Diverters Are Non-Negotiable
Perth roofs collect more than just rainwater. They collect dust, bird droppings and leaves, among other things, which decide to land up there between one storm and the next.
The first flush of rain washes all that nastiness straight off. And you absolutely do not want that going into your tank! This is where a first-flush diverter enters your system.
This is one of those components people attempt to skip just to save some cash. Do not allow that. Your tank water quality depends on it, and so does how long your pump lasts.
Pump Selection: The Heart of the System
A rainwater tank is just an expensive piece of garden art without a proper pump.
Getting the Pressure Right
You need enough pressure to actually use the water. Too weak, and your sprinklers dribble. Too powerful and you’re wasting electricity. Most Perth homes need pumps between 0.5 and 1.0 horsepower, depending on how far the water needs to travel and what you’re running.
Submersible vs External Pumps
Deciding on submersible or external pumps is one of those choices that stays with your system for years. Here’s what you should know:
- Submersible pumps get inside the tank, hence quieter operation but more difficult to service when something goes wrong.
- External pumps stay outside the tank, are noisier, but are easier to access when (not if) they need maintenance.
- If your tank is near outdoor entertaining areas, then noise levels matter. Submersibles are worth the extra cost.
- Maintenance accessibility: External pumps can be serviced without draining the tank or climbing inside.
- Budget considerations: External pumps are generally cheaper to purchase and replace.
We’ve installed both types across hundreds of Perth properties. The right choice depends on where your tank sits, how much noise you’ll tolerate, and whether you prefer easier maintenance or quieter operation.
Smart Pump Placement
We incorporate the installation of pumps as a component of landscaping. It is more prudent to conceal an external pump with intentionally designed garden beds than leave it protruding awkwardly against your house where everyone can see and hear it.
The right pump in the right location gives you that difference between a system you are proud of and one you wish were better planned.
Connecting to Your Garden: Irrigation Systems That Actually Work
Right, so you’ve collected the water. Now what?
The smartest approach is connecting your rainwater tanks to a properly designed irrigation setup in the Perth system.
Here’s what actually works in Perth:
- Drip line is your best option: drip line delivers water directly to plant roots with very minimal evaporation loss and high efficiency.
- Install automated controllers: Automated controllers manage timing and duration consistently. No more forgetting to water or leaving hoses running.
- Combine rainwater with smart technology. Most recent controllers adjust watering based on weather forecasts—one cycle is skipped when rain is coming.
- Zone your irrigation properly. Different areas need different schedules. Lawns, garden beds, and natives should be on separate zones.
- Include a backup mains connection. When your tank runs dry in late summer, automatic backup to scheme water keeps plants alive.
We have installed a large number of irrigation systems, and properties with properly designed setups use significantly less water overall.
Overflow and Mosquito Control
Perth summers mean standing water can become a mosquito breeding ground faster than you can say “dengue fever”.
Your overflow needs to drain properly, and mosquito prevention needs to be built into the system from day one.
Here’s what you need to consider:
| Component | Purpose | Why It Matters |
| Overflow pipe | Directs excess water away from tank | Prevents pooling and foundation damage |
| Mosquito screens | Covers all inlets and outlets | Stops mosquitoes entering to breed |
| First flush diverter | Blocks initial dirty water | Keeps tank water cleaner |
| Sealed tank lid | Prevents access to water | Eliminates breeding habitat |
| Absorption trench | Allows overflow to soak into garden | Useful water instead of wasted runoff |
Two overflow options that work
Some direct overflow back into stormwater. Others build absorption trenches that allow water to soak through garden beds. Both methods work, but Perth’s unique soil types will play a large role in determining which option suits your property best. Sandy soils have quick absorption, while for clay a different drainage solution is required. Ensure the overflow does not sit near your tank.
Mosquitoes can breed in surprisingly small amounts of water, and nobody wants that in their backyard. Every entry point to your tank needs proper screening, and the tank itself needs to be properly sealed. No gaps, no compromises.
The Perth Water Restrictions Reality Check
Water restrictions are a fact of life in Perth.
The Water Corporation has implemented ‘permanent’ water efficiency measures across Perth and Mandurah. These include the two-day-per-week sprinkler roster and the total winter sprinkler ban from June 1 to August 31 each year.
The beautiful thing with rainwater harvesting is that you can use tank water to irrigate your garden at any time outside the restricted hours. That’s huge for plant health because watering during cooler parts of the day means less evaporation and better absorption.
This is particularly important for newly installed landscapes. When we finish a construction project, the plants need consistent watering to establish properly. Rainwater systems give you the flexibility to maintain proper watering schedules regardless of what sprinkler roster you may be on.
Maintenance Nobody Tells You About
Rainwater systems do not need constant looking after. They just need regular maintenance.
Clean gutters before winter. Check screens. Empty first flush diverters. Inspect tank interiors every few years. Service pumps.
We get to see, through our maintenance programs, lots of neglected rainwater systems that have broken down in one way or another. We know that prevention is always less expensive than cure. A little bit of attention twice a year keeps everything running smoothly.
Cost Versus Benefit: Does It Actually Save Money?
Here’s the truth bomb: payback periods can be long if you only count water bill savings. But add in keeping expensive landscapes alive during restrictions, avoiding replanting costs from dead plants, increased property value, reduced stormwater runoff and environmental benefits, and then it starts to make sense.
We have worked on properties where established gardens represent $50k+ of plant material and hardscaping. A $5k rainwater system that protects that investment? That’s money management.
Integrating Rainwater Systems Into Landscape Design
This is where thinking holistically pays off.
Rather than treating your rainwater tank as an afterthought, we integrate it into the overall design from day one. Tanks can be buried, partially hidden, or even made into features. Underground tanks disappear completely but cost more. Aboveground tanks are cheaper but need visual consideration.
If we are involved from the concept stage, your rainwater system will become a feature of the landscape instead of something awkward tacked on at a later date. We have completed garden designs where tanks are hidden behind timber screens or living walls, and planted areas seem to merge seamlessly with them. The tank performs its function but does not dominate the visual space.
Perth-Specific Plant Selection
Waterwise gardening, Perth style, means choosing plants suited to our climate regardless of whether you have tanks or not.
Native WA species, Mediterranean plants, and drought-tolerant varieties all make sense here. Rainwater systems extend what’s possible, but they don’t make water infinite. Smart plant selection reduces overall water demand, meaning your tanks last longer through summer.
Get your garden ready for Perth’s summer by picking tough plants. Through our design consults, we specify the right plant for your particular site conditions—from full sun to shaded areas and considerations of water availability. It’s about setting up a landscape that looks good throughout the year without consuming “ridiculous” amounts of water.
Final Thoughts From Four Decades in Perth Landscapes
Rainwater harvesting for Perth homes is not rocket science. It simply involves understanding the particular climatic challenges facing this city.
We have watched water become more precious over the years. We have seen scheme water prices rise, and we have helped scores of Perth homeowners develop lush yet sustainable outdoor spaces that do not deplete bank accounts or the water supply.
If you are developing a new landscape or simply modifying your existing one, now is the perfect time to determine how rainwater fits into your entire plan. More than just purchasing a tank, it involves setting up an integrated system that indeed works with Perth’s climate.
Would you like to talk about how rainwater harvesting could work with your specific property? That is exactly the type of conversation we love having because creating gardens that thrive in Perth’s conditions is what we have been doing.
