Strengths

  • Can be diverted to recharge groundwater.
  • Simple technologies for locals to implement, and construction materials are readily available.
  • Provision of water at the point of consumption is convenient, and family members have full control of their own systems, which greatly reduces operation and maintenance problems.
  • Very low to negligible running costs.
  • Water collected from roof catchments is usually of acceptable quality for domestic purposes.
  • Reduces flow of pollutants to surface water.
  • Serves as a backup water supply during emergencies and natural disasters and mitigates flooding of low-lying areas.
  • Provides an independent water supply.

Limitation

  • The rooftops should be constructed of chemically inert materials such as wood, tiles, tin, aluminium, or fiberglass, and cleaned regularly to avoid adverse effects on water quality.
  • Unpredictable rainfall might pose a problem.
  • Rainwater harvesting systems require regular maintenance. They can become a breeding ground for rodents, mosquitoes, algae, insects and lizards if not properly maintained.

Rainwater harvesting (Rooftop)

Application: Aquifers, bore wells/dug wells, buildings, farms, houses, markets, and reservoirs

Description: Rainwater harvesting from a rooftop is one of the techniques to collect rainwater from surfaces on which rain falls, filtering it and storing it for multiple uses. The harvested water can be used for gardens, livestock, irrigation, domestic use after proper treatment, and indoor heating for houses. It can also be used as drinking water, to recharge groundwater and bore and dug wells and can be stored relatively long-term. The main components of a simple roof water collection system are the roof catchment area, conveyance system or gutter and piping connected to a container (jar, pot or tank).

Contribution to climate resilience: Rainwater harvesting improves water availability for agriculture, livestock, household use (washing, cooking) and personal consumption (with proper treatment). It consequently reduces pressure on other water sources such as groundwater. Construction materials for most rainwater harvesting technologies are locally available, and installation and repair can be undertaken by households, improving their ability to cope with and recover from emergencies.

Supplementary sources of information:

http://www.gdrc.org/uem/water/rainwater/introduction.html

http://www.watercache.com/education/rainwater/

http://www.conserve-energy-future.com/Advantages_Disadvantages_Rainwater_Harvesting.php

http://lms.sjp.ac.lk/fas/wordpress/?p=329

http://e-pao.net/epSubPageExtractor.asp?src=education.Science_and_Technology.Rainwater_Harvesting_and_its_Benefits

Background image credit: https://www.indiawaterportal.org/topics/rainwater-harvesting

This resilience-building measure is sourced from the Water Resource Adaptation Guide (2019) published by the National Council for Sustainable Development at the Ministry of Environment in Cambodia. The full Guide is available to download at URL https://ncsd.moe.gov.kh/sites/default/files/2019-10/Water%20Resources%20Adaptation%20Guide_March%202019_En.pdf