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Rainwater Harvesting

What is rainwater harvesting?

Rainwater harvesting is the capture and storage of rainwater for landscape irrigation, potable and non-potable indoor use, and storm water abatement. Harvested rainwater can be particularly useful when no other source of water supply is available, or if the available supply is inadequate or of poor quality.

Why is there so much interest of late in rainwater harvesting?

Rainwater harvesting is enjoying a revival in popularity for two reasons: its inherently superior quality and an interest in reducing consumption of treated water. Rainwater has long been valued for its purity and softness. It is slightly acidic, and is free from disinfectant by-products, salts, minerals, and other natural and man-made contaminants. Furthermore, rainwater harvesting is valued as a water conservation tool to reduce demand on more traditional water supply sources.

Are all rainwater collection systems above-ground?

While a vast majority of the rainwater collection systems installed are indeed above ground, there are systems available that can be installed below ground surface. Inground storage tanks tend to more expensive than aboveground tanks because of excavation costs and the need to have a more heavily reinforced tank.

Why should I be interested in rainwater harvesting when there is so much water already available for my use?

Rainwater harvesting provides us an opportunity to conserve and extend our existing resources.

Also, rainwater has some intrinsic qualities that should make it attractive to the user. It is pure, soft, and only slightly acidic. It is also free of disinfectant by-products, salts, minerals, and other natural and man-made chemicals that are typically added to water from centralized water supply systems. Plants tend to thrive under rainwater irrigation, appliances last longer because the water is salt-free, and the water tastes good because it is relatively free of chemicals.

Is collected rainwater safe to drink? Does it have to be inspected or tested before being used?

Collected rainwater is generally safe to drink after treatment. As rain falls through the atmosphere and on to the catchment surface it may pick up microbial and chemical contaminants and particulate matter. These contaminants must be removed before the water is used. Currently, there are no federal or state water quality standards for harvested rainwater. However, appropriate county health department and city building staff should be contacted for local testing requirements prior to using rainwater for drinking purposes.

What are some of the benefi ts of rainwater harvesting?

There are a number of benefi ts to using water from rainwater harvesting systems:

• The water is practically free: the only cost is to collect and treat it.
• The end use is located close to the source thereby eliminating the need for costly distribution systems. 
• Rainwater provides a source of water when a more traditional source such as groundwater is unavailable or the quality unacceptable.
• The zero hardness of rainwater helps scales from building up on appliances and so extends the life of appliances.
• Rainwater is free of sodium. 
• Rainwater is superior for landscape use and plants thrive on rainwater.
• Rainwater harvesting reduces fl ow to storm sewers and the threat of flooding.
• Rainwater harvesting helps utilities reduce peak demands during summer months. 
• By harvesting rainwater, homeowners can reduce their utility bills.




Current Issue: Africa Water & Sanitation & Hygiene December 2018 Vol.13 No.6