Water tank calculator

Whether you’re wanting to save on costs, water, or both, it’s important to understand how much water common household appliances use. From essentials such as showers and toilets to pools and spas, many appliances in, around and for your home can be connected to a rainwater tank. These usage estimates below will help you choose the right tank size for your space, whether you live in a house, townhouse, unit or flat.

Household Water Uses

Household Water UsesEstimated Water Usage (Litres)Estimated Water Usage (Imperial Gallons)
Dishwashers10-15L per cycle2.2 – 3.3G
Kitchen Sink Taps6-10L per minute1.3 – 2.2G
Washing Machine (top load)150-180L per load33 – 40G
Laundry Sink Taps6-10L per minute1.3 – 2.2G
Showers8 – 12L per minute1.8 – 2.6G
Baths80-100L per bath17.6 – 22G
Bathroom Sink Taps6-10L per minute1.3 – 2.2G
Toilets (full flush)11-13L per flush2.4-2.9G
Toilets (half flush)4-6L per flush0.9 – 1.3G
Filter Drinking Water Tap2 – 3L per glass (250ml)0.4 – 0.6G
Outdoor Taps15-20L per minute3.3-4.4G
Outdoor Sinks6-10L per minute1.3 – 2.2G
Hoses, Irrigation, Sprinklers15-20L per minute3.3 – 4.4G
Pressure Washes10-15L per minute2.2 – 3.3G
Pools & Spas100-200L per hour (top up)22 – 44G
Washing Machine (front load)50-80L per load11 – 18G
Garden features (ponds, fountains)10-20L per hour2.2 – 4.4G
Pull-down/Pull-out spouts taps6-9L per minute1 – 2G

Community spaces such as sports grounds, parks and public facilities often have higher and more varied water demands. Rainwater can be used to supply irrigation systems, outdoor showers, toilets and more. The following usage estimates aim to help you find the best sized tank that supports both day-to-day use and peak seasonal demand for your local community, business or property.

Community Water Uses

Community Water UsesEstimated Water Usage (Litres)Estimated Water Usage (Imperial Gallons)
Sports Field Irrigation System (e.g soccer pitch or AFL field)300 – 600 per hour (per hectare)66 – 132G
Outdoor Drinking Fountains1-3L per minute0.2 – 0.6G
Public Garden Fountains/Waterfalls20 – 50L per hour4.4 – 11G
Gym/Fitness Centre Showers40 – 60L per shower (6 – 10 min)8.8 – 13.2G
Picnic/BBQ Stations6 – 9L per minute1.3 – 2.0G
Public Toilets (Full Flush)6 – 9L per flush1.3 – 2.0G
Public Toilets (Half Flush)3 – 4L per flush0.7 – 0.9G
Dog Parks / Pet Washing Stations15 – 25L per use3.3 – 5.5G
Emergency Wash Stations / Fire Fighting Systems200 – 400L per hour44 – 88G
Public Beach Showers18 – 45L per use3.96 – 9.9G

Please note these estimated water usage figures on the above tables are based off average estimates and can vary depending on the specific model of the appliance, usage habits, and water efficiency ratings. Bushmans recommends always using a filter for water consumption.

Alternatively, use our more in-depth water tank calculator below. Find out how much water you use and which size tank you need.

How to use the calculator in 3 easy steps:

Step 1: Fill out how many times per day you perform certain indoor activities.

Step 2: Fill out how many times per day you perform certain outdoor activities.

Step 3: Fill in your roof area (m3) and the average rainfall in your location (mm).

Step 1: Fill out how many times per day you perform certain indoor activities.

Indoors

ActivityTimes Per DayActivityLtr Per DayLtr Per Year
Shower15 Litres per minute
Bath150 Litres
Dishwasher30 Litres per load
Front Load Washing Machine80 Litres per load
Top Load Washing Machine100 Litres per load
Brushing Teeth with tap running5 Litres per person
Drinking, Cleaning, Cooking per person10 Litres per day, per person
Hand Basin Use5 Litres per time
Toilet Flush single6 Litres per time
Toilet Flush half3 Litres per time

 

Step 2: Fill out how many times per day you perform certain outdoor activities.

Outdoors

ActivityTimes Per DayUnitsLtr Per DayLtr Per Year
Garden SprinklerGarden hose 15L /min.
Car Wash200 Litres
Hosing Hard Surfaces 15 litres per minute
Drip Systemlitres per hour
Filling poolSize in Litres

 

Step 3: Fill in your roof area (m3) and the average rainfall in your location (mm).

Size Of Water Tank

Roof area (m3)Average Annual Rainfall (mm)Amount of rain harvested (litres)Minimum Tank Size
   Assume the tank can fill 3 times
per year (Depends on rainfall and usage patterns)

 

Total Per Annum

Your Calculation Summary

Litres per dayLitres per yearRain harvestedTank Size (litres)

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