Rain Water Harvesting – A necessity

In most urban areas, population is increasing rapidly and the issue of supplying adequate water to meet societal needs and to ensure equity in access to water is one of the most urgent and significant challenges faced by decision-makers. With respect to the physical alternatives to fulfil sustainable management of freshwater, there are two solutions:

1-       finding alternate or additional water resources using conventional centralised approaches;

2-      better utilising the limited amount of water resources available in a more efficient way.

To date, much attention has been given to the first option and only limited attention has been given to optimising water management systems.

Among the various alternative technologies to augment freshwater resources, rainwater harvesting and utilisation is a decentralised, environmentally sound solution, which can avoid many environmental problems often caused in conventional large-scale projects using centralised approaches.

Introduction

Rainwater harvesting, in its broadest sense, is a technology used for collecting and storing rainwater for human use from rooftops, land surfaces or rock catchments using simple techniques such as jars and pots as well as engineered techniques. Rainwater harvesting has been practiced for more than 4,000 years, owing to the temporal and spatial variability of rainfall. It is an important water source in many areas with significant rainfall but lacking any kind of conventional, centralised supply system. It is also a good option in areas where good quality fresh surface water or groundwater is lacking. The application of appropriate rainwater harvesting technology is important for the utilisation of rainwater as a water resources

The Global Water Crisis

Rapid population growth, combined with industrialisation, urbanisation, agricultural intensification and water-intensive lifestyles is resulting in a global water crisis. About 20 per cent of the population currently lacks access to safe drinking water, while 50 per cent lacks access to a safe sanitation system. Falling water tables are widespread and cause serious problems, both because they lead to water shortages and, in coastal areas, to salt intrusion. Both contamination of drinking water and nitrate and heavy metal pollution of rivers, lakes and reservoirs are common problems throughout the world. The world supply of freshwater cannot be increased. More and more people are becoming dependent on limited supplies of freshwater that are becoming more polluted. Water security, like food security, is becoming a major national and regional priority in many areas of the world.

Advantages of Rainwater Harvesting

Rainwater harvesting systems can provide water at or near the point where water is needed or used. The systems can be both owner and utility operated and managed. Rainwater collected using existing structures (i.e., rooftops, parking lots, playgrounds, parks, ponds, flood plains, etc.), has few negative environmental impacts compared to other technologies for water resources development. Rainwater is relatively clean and the quality is usually acceptable for many purposes with little or even no treatment. The physical and chemical properties of rainwater are usually superior to sources of groundwater that may have been subjected to contamination.

Some Other Advantages of Rainwater Harvesting Include:

a.  Rainwater harvesting can co‐exist with and provide a good supplement to other watersources and utility systems, thus relieving pressure on other water sources.

b.  Rainwater harvesting provides a water supply buffer for use in times of emergency orbreakdown of the public water supply systems, particularly during natural disasters.

c.  Rainwater harvesting can reduce storm drainage load and flooding in city streets.

d.  Users of rainwater are usually the owners who operate and manage the catchmentsystem, hence, they are more likely to exercise water conservation because they knowhow much water is in storage and they will try to prevent the storage tank fromdrying up.

e.  Rainwater harvesting technologies are flexible and can be built to meet almost anyrequirements. Construction, operation, and maintenance arenot labour intensive.