Homeowners
Plan rainwater storage for the garden, toilets, laundry and other suitable non-potable uses. See how much your roof and tank could have supplied, and whether a larger tank would help.
About the planner
Plan with the whole rainfall story.
Explore how your roof, tank and water demand could have worked together through Australia’s historical wet and dry periods.
Built for your property
Who is this planner for?
From a suburban rainwater tank to an off-grid water supply, understand how your system could have performed in the past.
Rural and acreage properties
Explore storage for a larger home or shed. See how roof catchment area, tank capacity and daily demand interact through prolonged dry periods.
Off-grid living
When rainwater is your primary supply, explore historical shortages and how your available catchment and storage would have met your nominated demand.
Existing tank owners
Check how your current tank would have performed in the historical record. Compare it with tested alternatives to see whether more storage would have made a meaningful difference.
Why historical rainfall matters
Average annual rainfall doesn’t tell the whole story.
Two places with similar yearly totals may need different storage. Rain may fall in different seasons, dry spells can last longer, and some years are much drier than others.
A wet spell can fill a tank so that extra water overflows, while demand continues during days without rain. Annual averages cannot show when those shortfalls happen.
The planner simulates collection, storage, demand and shortages using 30 scored years of daily historical Australian rainfall. It shows how a system would have performed in that record; it cannot guarantee future supply.
Make a more informed choice
What can this planner tell you?
01
Find a practical tank size
Explore rainwater tank sizing for your available roof area and daily water demand.
02
Understand historical shortages
See how often demand was not fully supplied and how long shortages lasted.
03
Identify catchment limitations
Understand when your roof collects too little rain to meet demand, even with more storage.
04
Compare tank sizes
Use the water tank reliability graph to see where larger tanks bring smaller gains.
05
Evaluate an existing system
See whether a larger tank would have meaningfully improved your system’s historical performance.
How does it work?
Enter an Australian location, roof catchment area and daily water demand. The planner retrieves historical daily rainfall from SILO and simulates collection, storage, consumption, overflow and shortages. It compares tank capacities or evaluates your existing tank, showing historical performance rather than guaranteeing future supply.
Limitations
Historical rainfall data is an estimate of past conditions and may differ from rainfall recorded at a particular property. Past conditions cannot guarantee future water availability.