Install water tanks connected to toilets

For businesses with the capacity to install water tanks at their workplace, plumbing then to the toilet system can remove costs for years to come.

In the pursuit of profit in your business, removing ongoing costs can be as effective as increasing sales. By insulating your bottom line from ongoing water use, and increasing water costs, you are increasing the profitability and durability of your business.

For hospitality businesses (bars, restaurants, etc…) plumbing the toilet to a free source of water collected from your roof via a water tank is simple efficiency and logic.

How to do it now!

Investigate the benefit of installing a rainwater harvesting system in your workplace, and connect it to your toilets. Understand your situation, 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)/1000
    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. The Australian Government has announced that it will no longer be providing rebates for rainwater tanks or greywater systems under the National Rainwater and Greywater Initiative however a number of state governments continue to offer generous rebates for installing a rainwater tank or greywater systems. Check our rebates and assistance page for more details. Smart Watermark lists local government rebates that may also 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 facilities 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 workplace should you sell. This equates to a 5.5 per cent annual return plus your investment back.
  5. Align the system installation with your next workplace renovation. Renovations provide a unique opportunity to re-engineer your plumbing to suit the water-scarce world in which we live. The specific design of your water system would depend on your needs and the rainfall in your area.

Additional resources

  • For more information on selecting a rainwater tank that’s right for your conditions including what size tank you will need, check out the Savewater website.

Why is this action important?

Sustainable living guide