Roof Water Harvesting (RHW): Limitations of RHW

Water professionals all over the world are increasingly worried about the scarcity of water. According to the

UN World Water Development Report of 2003

, various factors like climate change, pollution and population growth will result in a sharp decline in the amount of water available per person in developing countries. Hence,

Domestic Roof Water Harvesting (DRWH)

is an effective source of water which meets the local water needs. But roof water harvesting has its own drawbacks. Read on to know more about the limitations of roof water harvesting.

‘Rainwater harvesting’ is a term which covers all those techniques in which the rain water is collected and stored for general use. Small reservoirs are constructed to collect run-off water so that it can be used for micro-irrigation and cattle. Even this run-off water is collected from impermeable surfaces and from roofs. Hence, roof water harvesting is a part of rainwater harvesting which has its own importance.

Limitations of RHW

It also carries the possibility of failure just like all other sources of domestic water. The risk and reliability associated with this technique include:


  • This occurs when the water storing containers such as tanks run dry due to a long spell of dryness. This event is quite expected. Therefore, such type of RHW design is needed that can give a known availability of water. In such system, we can anticipate the performance.
  • During such dry spells, water consumption should be reduced or other sources of water should be used to refill the RHW tanks. However, RHW is highly vulnerable than other sources of water.

Sudden Failures

These failures can occur at any time such as cessation of management, breakages, storm and earthquake. But one advantage of RHW system is that it can withstand such type of disasters as it is not interconnected. Also, it is widely distributed. A few disasters can, however, disable the RHW systems.

Gradual Changes

They pose a bigger threat to reliable water sources than other disasters. These include:

  • Mechanical breakdown and infrastructure breakdown
  • Inadequate water supply for a large population size
  • Contamination of rivers or aquifers by human activities or natural processes

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