Rainwater harvesting: Playing a valuable role in increasing the resilience and sustainability of water supply

South African is a water scarce country and studies indicate that 98% of available water supplies are already exploited. In addition, a number of South African cities, such as Johannesburg, are vulnerable to water shortages if a severe drought occurs (Department of Environmental Affairs, 2011).

NY Times

Therefore, it is important to understand how water can be used as efficiently as possible and to explore alternatives to municipal piped water supplies. Rainwater harvesting provides a simple way of capturing and storing water which can be used to supplement, or replace municipal water supplies. It can be used to reduce the pressure on municipal systems and provides a valuable buffer for households and businesses against drought and local water shortages.

This article describes how rainwater harvesting can play a valuable role in increasing the resilience and sustainability of water supply. The different types of rainwater harvesting systems are described and advantages and disadvantages of the technology listed. Some of the key design and operational principles are presented to enable the practicality and applicability of systems to be understood. Finally, conclusions are drawn and policy, and other, recommendations are made to support the increased adoption of rainwater harvesting systems in South Africa.

Full article can be accessed here

Water in Sustainable Buildings

Water systems in sustainable buildings are different in a number of ways from conventional buildings. Characteristics of water systems in sustainable building include:

• Self sufficiency: Sustainable buildings may aim to meet all, or most of their water needs from rainwater harvesting.  
• Water quality: The quality of water is matched with use. For instance, the best quality water may be used for drinking and cooking and poorer quality water, such as grey water, used for flushing toilets and irrigation. 
• Onsite retention: In natural environments vegetation and soil absorb and retain a large proportion of rainwater that falls on to it. Sustainable buildings aim to emulate this by ensuring that buildings and sites absorb and retain rainwater on site and avoid generating large quantities of runoff.
• Evaporation and transpiration: Air can be cooled and the humidity increased through evaporation of water and transpiration from plants. This may be used in sustainable buildings to improve comfort levels without the use of mechanical systems.

More information on water systems in sustainable building can be accessed here.