Harvest and use your rainwater

Install a rainwater tank to collect and store rain hitting your roof and use it to water your garden, wash your clothes or fill your toilet.

By capturing and using the rain that falls on our houses – water that currently flows into the stormwater drain – we are taking another step in increasing our water efficiency and conserving this precious resource. Have a plumber redirect your down pipes into a tank for storage and install pumps and pipes to service some of your household water needs. By these simple actions, most Australian households would save at least 45,000 litres and hundreds of dollars each year.

How to do it now!

Investigate the benefit of installing a rainwater harvesting system in your home, explore government rebates and think medium to long term.

  1. Understand the rainfall capturing capacity of your roof

    By using the monthly rainfall averages for your area and the surface area of your roof you can calculate the average amount of water you are likely to collect into your water tank each month. The following formula calculates the annual capture potential of your roof:Potential estimated average annual capture amount (KL) = roof area (in square metres) x average annual rainfall (in millimeters)/1000The Alternative Technology Association has developed Tankulator, a useful online calculator for determining the optimum water tank size for your specific location, roof area and usage profile.For example, a roof area of 250m2 is an area that receives annual rainfall of 600mm will be able to capture 150,000 litres per annum. Assuming the rainfall is spread evenly over the year, i.e. 12,500 litres per month, and regular use of this water is in toilets and garden watering, a 25,000 litre capacity tank may be sufficient to maximise water capture. However, if the rainfall pattern over the year was more skewed to certain months (i.e winter) then the tank size would need to increase to store more water for the dryer periods.The Bureau of Meteorology website list the annual, monthly and seasonal rainfall averages for most parts of Australia.Developing an understanding of your monthly average rainfall capture will enable you to identify what sized tank will maximise your rainwater capture and reuse.

  2. Seek advice and a quote

    Contact a local rainwater tank and tank-to-toilet installation specialist in your area to get some expert advice and a quote on installation.

  3. Explore government rebates and assistance

    Check the Smart Watermark site for lists local government rebates that may be available.

  4. Calculate the cost, benefit and return on investment

    By measuring the water bill savings, rebates and increased home value against the cost to purchase and install a rainwater harvesting system you can calculate the financial benefit of this investment. For example, installing a 5,000 litre tank connected to the toilet and garden may cost $10,000 with a $1,000 rebate and reduce your water bill by $500 per annum.

    In addition, a recent study by Energy Partners in Canberra found that a one-star improvement in a home’s energy rating coincides with an average increase in advertised sale price of around $15,000. Therefore, the above investment will add at least $10,000 of value to your house should you sell. This equates to a 5.5 per cent annual return plus your investment back.

Why is this action important?

Sustainable living guide