In many regions of the world, clean drinking water is not always available and this is only possible with tremendous investment costs and expenditure. Rainwater is a free source and relatively clean and with proper treatment it can be even used as a potable water source. Rainwater harvesting saves high-quality drinking watersources and relieves the pressure on sewers and the environment by mitigating floods, soil erosions and replenishing groundwater levels. In addition, rainwater harvesting reduces the potable water consumption and consequently, the volume of generated wastewater.
Application areas
Rainwater harvesting systems can be installed in both new and existing buildings and harvested rainwater used for different applications that do not require drinking water quality such as toilet flushing, garden watering, irrigation, cleaning and laundry washing. Harvested rainwater is also used in many parts of the world as adrinking water source. As rainwater is very soft there is also less consumption of washing and cleaning powder. With rainwater harvesting, the savings in potable water could amount up to 50% of the total household consumption.
Criteria for selection of rainwater harvesting technologies
Several factors should be considered when selecting rainwater harvesting systems for domestic use:
• type and size of catchment area
• local rainfall data and weather patterns
• family size
• length of the drought period
• alternative water sources
• cost of the rainwater harvesting system.
When rainwater harvesting is mainly considered for irrigation, several factors should be taken into consideration. These include:
• rainfall amounts, intensities, and evapo-transpiration rates
• soil infiltration rate, water holding capacity, fertility and depth of soil
• crop characteristics such as water requirement and length of growing period Although rainwater can be harvested from many surfaces, rooftop