How much rain your roof catches in a typical Maleny year, which months fill the tank, and how far that water stretches — plus how much has actually fallen lately.
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From Town Tools. For the current version, visit https://www.town.tools/maleny-queensland-au/tank-water-planner
Most homes around Maleny — and nearly every rural property off the town main — run on rainwater tanks. Up here the rain itself is rarely the problem: about 2,000 mm falls in a typical year, most of it between December and March. The catch is bridging the dry stretch from June to September, when little falls and the tank just draws down. Put in your roof and household to see how much a typical year catches, which months top the tank up, and how far that water stretches.
In a typical year, this roof could catch about
337,300 litres of water
from about 1,984 mm of rain a year
Days of household water
~1,124 days
for 2 people at 150 L a day
Bought water it replaces (a water-carter delivery)
≈ 25.9 a year
one 13,000 L load
Wettest month
54,000 L
the most a tank would bank at once
When the tank fills
Litres this roof catches each month of a typical year. The rains do the work in a few months — storage carries you through the dry ones.
JanJan: 48,200 L
FebFeb: 54,000 L
MarMar: 48,800 L
AprApr: 32,100 L
MayMay: 23,900 L
JunJun: 18,500 L
JulJul: 14,800 L
AugAug: 11,000 L
SeptSept: 10,900 L
OctOct: 18,400 L
NovNov: 23,200 L
DecDec: 33,500 L
And right now
About 57 mm of rain has fallen in the last 30 days — enough for this roof to have caught roughly 9,600 litres.
These are estimates, not a promise
The catch is plain arithmetic from your roof size and average rainfall — real water depends on your roof, gutters, the first wash thrown off a dusty roof, and how big a tank you have to hold it. Treat it as a starting point for sizing a tank, not a guarantee.
Live rainfall from Open-Meteo (CC BY 4.0) — a weather-model estimate for the area, not a rain gauge on your street. Updated .
Rain off a roof is not drinking water
Rain off your roof is not automatically safe to drink. Queensland Health advises using town water for drinking wherever you're connected; for tank-only homes the health risk stays low if the tank is well kept — insect-proof mesh (1 mm or finer) on every opening, gutters and the first-flush cleaned every few months, and the tank de-sludged every 2–3 years. Infants, the elderly, and people with weakened immune systems should boil and cool tank water, or use a disinfection system that meets AS/NZS 4348.
Rainfall varies a lot around here
These are the long-term monthly averages for Maleny township (Bureau of Meteorology, Tamarind St, 1915–2017). Real rain swings a lot from year to year and even across the Blackall Range — a dry summer changes everything. Treat the figures as a typical year, not a promise for your roof.
What goes into the numbers
Why not every drop is caught
Assumes a hard metal (Colorbond) or tile roof with gutters in good order. Some rain is lost to the first flush, gutter overflow in a downpour, and splash — so the catch is a little under the rain that lands.
How much water a person uses
150 litres a person a day is Seqwater's voluntary “Target 150” for all household uses — drinking, washing, laundry, the garden. Tank households watching their supply often manage on well under that; set it to match how your place really uses water.
Worth knowing
When the tank fills — and when it doesn't
Maleny's rain is summer-heavy: December to March each bring 200–320 mm and will top a tank up fast, while June to September average under 110 mm — August and September barely 65 mm. A tank that's full coming out of autumn has to carry the household through that dry stretch, so the number that matters most isn't the yearly total but whether your storage is big enough to bridge winter.
Keeping tank water safe
Check the first-flush diverter and that every tank opening has 1 mm insect mesh every few months; clean the roof and gutters and look for animal or bird access twice a year; and check inside for sludge every 2–3 years, de-sludging if it covers the bottom. Queensland Health does not recommend routinely chlorinating roof water.
If you run low in a dry spell
Rural properties off the town main can order a water-carter delivery (a truck load is roughly 13,000 litres) to top a tank up through a dry winter or drought — worth lining up before the tank runs down, as carters get busy. Homes connected to town water draw treated supply from Baroon Pocket Dam through Unitywater and aren't affected the same way. Get Ready Maleny.