Above: Rainwater harvesting on a commercial farming shed. Picture used courtesy of Helen Gordon, WWF-SA.
Rain water harvesting (RWH) is increasingly being accepted as a practical method of providing both irrigation and potable water in agricultural and development projects throughout the world.
Enough rain falls on the African continent to supply the water needs for 13 billion people, twice the current world population. However, little of the rainfall is collected or stored through sustainable methods, such as small and large-scale rainwater harvesting.
In South Africa, where the backyards of rural homesteads add up to a whopping 200 000 hectares (i.e. double the current area under smallholder irrigation), the potential impact on food security is more than significant.
The level of economic activity has been shown to double in rural villages with access to more water. This has a direct impact on poverty. Every household with a roof can potentially harvest and store rainwater.
RWH has wide application also in urban and peri-urban areas where the quantity, reliability and quality of piped water are sometimes questioned. Some rainwater might require treatment before it is considered suitable for drinking. So-called “appropriate technology” methods (e.g. as solar water disinfection) provide low-cost disinfection options for treatment of stored rainwater for drinking.
Source: UN Environment Programme (UNEP) “Environmental Food Crisis” report, May 2009; http://en.wikipedia.org/wiki/Rainwater_harvesting; Tsepho Khumbane, Trustee of The Mvula Trust (adapted)
National strategy and government contact
The Department of Water & Sanitation (DWS) , in partnership with Department of Forestry, Fisheries and the Environment (DFFE), has rainwater harvesting as a key component of South Africa’s water resources and efforts to enhance climate resilience. The strategy will provide guidance towards the mainstreaming of RWH in South Africa. This National RWH Strategy helps serve as the guiding tool for district and local municipalities to effectively and economically put RWH into practice.
Several municipalities now use roof rainwater tanks for domestic purposes. These have been found to be particularly effective when used in conjunction with other water supply options. A resource guideline was developed in the 2017/2018 financial year to assist municipalities that are providing rainwater harvesting systems to communities as an interim service or to reduce demand on their water supply systems with best practices.
Find the “Rainwater harvesting” heading in the latest Water & Sanitation chapter of the government Yearbook on www.gcis.gov.za.
Source: The notes on Rainwater harvesting in the Water & Sanitation chapter of the 2019/20 government Yearbook on www.gcis.gov.za.
Role players
Rainwater for drinking should be carefully stored and treated prior to consumption. Several technologies exist for home treatment including: ozone sterilisation, UV, distillation. Fairly simple sand filters followed by household chlorine may also be utilised.
Websites and publications
- Order online at www.arc.agric.za, call 012 842 4017 or send an email to stoltze [at] arc.agric.za for the following publications, available from the ARC Agricultural Engineering: Water harvesting techniques and Reënvalopvangstegnieke.
- Kejafa Knowledge Works stocks the publication Water Harvesting Techniques. Contact them at 014 577 8006 or visit www.kejafa.com.
- Various reports on in-field rainwater harvesting and conservation are available from the Water Research Commission. Visit www.wrc.org.za.
- www.harvesth2o.com – the “online rainwater harvesting community” (USA based)
- Find the Info Pak “Collecting rainwater from your roof” from the Department of Agriculture at www.nda.gov.za.
- Contact the Environmental Monitoring Group (EMG) for the DVD “Rainwater harvesting – An illustration of what can be done, and is being done at a community level”. See www.emg.org.za.
Some articles:
- Leonard L. 2023, August 23. “Water Harvesting 101: Everything You Need to Know”. EcoWatch. Available at www.ecowatch.com/water-harvesting-facts-ecowatch.html
- Reporter. 2020, November 25. “Rural communities urged to harvest rain water”. SA News. Available at www.sanews.gov.za/south-africa/rural-communities-urged-harvest-rain-water
- Botha L. 2019, June 8. “Water management: rainwater harvesting and better storage”. Farmer’s Weekly. Available at www.farmersweekly.co.za/farm-basics/how-to-business/water-management-rainwater-harvesting-and-better-storage/
- Home Insulations. 2018, February 15. “Rainwater harvesting and storage tanks”. Available at www.homeinsulations.co.za/renewable/rainwater-harvesting-storage-tanks/
