QTank Monthly Offer Terms Q Tank Home Page
Choosing your water tank

Which size of tank do I need?


When considering what size water tank to buy, consider:

  • what you plan to use the water for
  • how many people will be using the water
  • the average annual rainfall for your area (see the Australian Bureau of Meteorology)
  • the size of your roof
  • the number of downpipes that you would connect to your rainwater tank.

Q Tank has a range of rainwater tank sizes to suit your water collection needs. A 3,000L tank is ideal for outdoor water use, such as plant watering, while a 5,000 - 10,000L water tank will hold enough to service your water needs - inside and outside the home.

Once they install a rainwater tank, many people discover a great number of uses for the rainwater they collect. Consider installing the largest tank you can fit within your available space.


How much water would I collect from my roof?


Rainwater tanks generally collect one litre of water for every millimetre of rain that falls on every one m2 on your roof. For example:

  • a short rain shower that dropped 1mm of rain on a 100m2 roof would collect 100L of water in your tank
  • a heavier shower that dropped 25mm of rain would collect 2,500L of water in your tank

Calculate your rainfall for the year by multiplying the number of square metres on your roof by the average annual rainfall in your area.


Where would I position my tank?

  • A water tank is ideally positioned near one or more downpipes - walk around your home to identify where the downpipes are located
  • To get a feel for the size of your tank, use a garden hose or rope as a line marker to measure out its diameter
  • All Q Tanks fit under the eaves of a standard single storey house
  • Please note that water tanks cannot be positioned over sewer mains
  • Your watertank will need to sit on a base. Read our installation page for more information

Is there anything else I should consider?


You may find the Queensland Government's 'Homeowners Rainwater Tank Checklist' (PDF 91Kb) useful to read before ordering.

Please contact us at Q Tank if you have any questions - we'd be happy to help.