Rooftop Rainwater Harvesting

Rooftop Rainwater Harvesting & Advantages of Rainwater Harvesting

Rooftop Rainwater Harvesting

Rooftop rainwater harvesting is the way of collecting, channeling and storing rainwater from rain downpour for human use. The rooftop rainwater harvesting system could be a plastic storage tank, underground storage tank, masonry made, or it might be just a water bucket, standing underneath a roof without a gutter.

Rainwater harvesting is one of the oldest and simplest ways of self-supply of water for domestic, and residential and commercial projects usually financed by the water user. But larger systems for hospitals, schools, and other public facilities can run up costs and can be financed by organizations, companies, and governments.

A rainwater harvesting systems use building roofing surfaces, such as roofs sheets, paving materials and exterior walls to divert rainwater and store the water in above-ground or underground or tanks to be used later.

These harvesting systems require an intentional design process to make that water can be supplied of the appropriate quality and quantity as expected.

Rainwater Harvesting Diagram

Rooftop Rainwater Harvesting

One method of collecting rooftop water is where any suitable roof surface like metal sheets (mabati) tiles, gutters, plastics, etc. These can be used to intercept the rainwater flow together with the use of downpipes and gutters.

Gutters and downpipes can be made from mabati, wood, plastic, bamboo, PVC or galvanized iron to provide homes with clean water, that can be treated and stored for human consumption.

Rooftop rainwater harvesting is one of the economically viable and optimistic ways of rainwater harvesting.

Sustainability of Rainwater Harvesting

 Rainwater harvesting is one of the best alternatives for supplying water in the face of increasing demand and water scarcity. The need for water supplies, increasing impact of the environment from big water projects and deteriorating water quality, affects the ability to meet the demand for fresh water from traditional water sources. Rainwater harvesting is a huge opportunity for the augmentation of water supplies allowing the same time for self-reliance and sustainability.

Cost of Rainwater Harvesting

 The costs associated with rainwater harvesting system are for installation, operation and maintenance. Of the expenses for installation, the storage tank represents the largest investment which can vary between 300-45% of the total cost of the system dependent on system size. A pump, a pressure controller and fittings in addition to plumber’s labour, represent other significant costs of the investment.

Rooftop Rainwater Harvesting  Filtration

Rainwater collected  from the roof is usually clean and pure. But, there are many finer substances, which get mixed up with this rain water on the roof  like leaves, dust, bird droppings, debris, etc.. These purities and contaminants need to be sieved and purified  before the rainwater is stored. There are many filtration systems  and some are

  • Sand bed filter
  • PopUp filter
  • Stabilization tank

Advantages of Rooftop Rainwater Harvesting System

  1. Rooftop rainwater harvesting promotes water conservation and eliminates water bills
  2. Rooftop rainwater harvesting reduces on-road flood water and mitigates soil erosion in the locality
  3. Rooftop rainwater harvesting is not expensive and not complicated to implement
  4. Rooftop rainwater harvesting requires less or no maintenance
  5. A rainwater harvesting system reduced the usage of potable water for different purposes
  6. A rainwater harvesting system can provide water for farm and irrigation during dry seasons
  7. Reduces water consumption by up to 40%
  8. Rooftop rainwater harvesting offers potential cost savings especially with rising water costs.
  9. Rooftop rainwater harvesting provides safe water for human consumption after proper treatment.
  10. A rainwater harvesting system encourages water storage
  11. A rainwater harvesting system helps in eliminating rooftop water pooling and therefore eliminate roof leakages
  12. Rainwater is a relatively clean and free source of water.
  13. Rainwater harvesting provides a source of water at the point where it is needed.
  14. Rooftop rainwater harvesting is socially acceptable and environmentally responsible.
  15. Rooftop rainwater harvesting promotes self-sufficiency and conserves water resources.
  16. Rainwater is friendly to landscape plants and gardens.
  17. Rooftop rainwater harvesting uses simple, flexible technologies that are easy to maintain.
  18. Low maintenance costs.

Disadvantages of Rooftop Rainwater Harvesting

  1. The success of rainfall harvesting often depends on the frequency and amount of rainfall; therefore, it is not a dependable water supply source in times of dry weather or prolonged drought.
  2. Storage tanks can be unsafe for animals and children if proper access protection is not provided.
  3. Leakage from channeling system can cause the deterioration of load bearing slopes.
  4. Possible contamination of water may result from dust, animal wastes and vegetable matter.
  5. Rainfall harvesting systems like gutters increase construction costs and may have an adverse effect on home ownership. Systems may add 3% to 10% to the cost of a construction.
  6. Where treatment of the water prior to potable use is infrequent, due to a lack of adequate resources or knowledge, health risks may result; further, cisterns can be a breeding ground for mosquitoes.
  7. Rainfall harvesting systems may reduce revenues to public utilities.

Rooftop rainwater harvesting measures need to be given priority in the drought prone regions and should be incorporated in the watershed development programs. A rooftop rain water harvesting measures helps in fulfilling the domestic water need as well improving the ground water level by few meters.



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