The JoJo rainwater harvesting calculator
The smart way to determine the tank size you require
Rainwater harvesting remains the simplest and most efficient way to collect FREE rainwater for a multiple of domestic uses. For most houses, 90% of the water that falls on the roof inevitably finds its way into the downpipes. Everyone should take advantage of this FREE water supply from the sky by simply connecting a rainwater-harvesting tank to a downpipe.
But, most often, it’s the size of the tank required that causes the biggest headache because it’s important to balance supply and demand with the right sized tank(s) so that there’s adequate water supply during long dry periods. That is why JoJo Tanks designed a rainwater-harvesting calculator that allows you to easily establish the amount of water you are able to capture on an annual basis and the ideal size of the tank(s) you would need to install. The calculation does take into account the efficiency factor of different roof materials to capture water. This is how you do it:
- Go to the JoJo Tanks website www.jojotanks.co.za and click on the Rainwater Harvesting calculator tab.
- Identify your region and the town closest to you on the provided map.
- Click on the name of the town in the dropdown menu
- Insert the total surface of your roof in square meters (m2) in the space provided. If in doubt, just pace out the length and width of the house.
- Insert your average monthly water consumption in liters in the space provided. You can get this from your municipality bill.
- Finally click on the tab ‘Calculate your average rainfall and ideal tank size’ to access the liters of rainwater you will be able to capture over a year, the storage capacity you’ll need to provide for and the suggested JoJo tank sizes.
Disclaimer: The values calculated here should be taken as a working guide, it does not take into account other effects (such as drought conditions) and how complete the source data coverage is.