Rainwater harvesting is the simple process or technology used to conserve Rainwater by collecting, storing, conveying and purifying of Rainwater that runs off from rooftops, parks, roads, open grounds, etc. for later use. It describes processes in which precipitation that falls on a site is diverted, captured, and stored for use on-site, as opposed to allowing it to run off, evaporate, or infiltrate into the soil. Depending on its intended use, the captured precipitation may require treatment. Rainwater harvesting can include capture rainwater from surface water runoff.

The rainwater harvesting is one of the best systems practiced and followed to support the conservation of water. Today, scarcity of good quality water has become a significant cause of concern. However, Rainwater, which is pure and of good quality, can be used for irrigation, washing, cleaning, bathing, cooking and also for other livestock requirements.

Rainwater harvesting is a sustainable process which helps to preserve water for future needs. Water scarcity is a major concern in today’s situation. The process of rainwater harvesting is a good way to conserve water.

The process of rainwater harvesting involves the collection and the storage of rainwater with the help of artificially designed systems that run off naturally or man-made catchment areas like- the rooftop, compounds, rock surface, hill slopes, artificially repaired impervious or semi-pervious land surface.

Several factors play a vital role in the amount of Rainwater Harvesting. Some of these factors are:

  • The quantum of runoff
  • Features of the catchments
  • Impact on the environment
  • Availability of the technology
  • The capacity of the storage tanks
  • Types of the roof, its slope and its materials
  • The frequency, quantity and the quality of the rainfall

 

The advantages of rainwater harvesting are:

  • It is cost-effective
  • Conserves water
  • A source of water for landscape irrigation
  • It is a simple method and easy to practice
  • It reduces soil erosion and pollution of water bodies due to fertilizers and pesticides

 

In addition to the great advantages, the rainwater harvesting system has a few disadvantages like unpredictable rainfall, unavailability of the proper storage system, etc.

Some disadvantages of the rainwater harvesting process:

  • Regular Maintenance is required.
  • Requires some technical skills for installation.
  • Less or no rainfall can reduce the supply of Rainwater.
  • If the plant is not installed correctly, it may attract mosquitoes and other waterborne diseases.
  • One of the problems of the rainwater harvesting is limitation of storage.

 

According to a study by the Institute of Water Modeling based in Bangladesh’s capital city, its groundwater level is falling by three meters per year. Population has increased and industry has expanded, river water has become contaminated with industrial waste. Today, groundwater is expected to satisfy over 80% of the city’s water supply. To use groundwater, we need to cost more as we need more energy, more electricity.  But about 150 billion liters of rainwater can be harvested during the monsoon season in Dhaka city alone and this process is both eco-friendly and cost effective.

Rainwater harvesting is therefore a potential option of water supply to the coastal and arsenic affected rural communities in Bangladesh as Dhaka Water Supply and Sewerage Authority (WASA) have shown that rainwater is free from arsenic contamination and the physical, chemical and bacteriological characteristics of harvested rainwater represent a suitable and acceptable means of potable water. Rainwater harvesting, low-cost systems that collect and store rainwater for year-round use, offers a cost-effective and practical solution to ease water crisis.