Rainwater Harvesting

Rainwater harvesting is the collection and storage of runoff rainwater from any flat surface. Water harvesting is done mainly in rain deficit areas of the world to use the stored water throughout the year or during water scarcity. Water plays a significant role in the life of all living organisms since it is a valuable natural resource. We know that 70% of our planet is covered with water, out of which freshwater is about 2.5%. But the rate of water consumption is increasing with the increase in population; because of limited fresh water and water scarcity, people are forced to harvest the natural source of freshwater, rainwater.

Rainwater Harvesting System

A rainwater harvesting system is a technique to collect rainwater for future use. Different designs of the system have various benefits in a rainwater harvesting system. There are seven types of rainwater harvesting systems. The first type is the water butt system; it is a basic system. The butt collects the rainwater in a container, either from pipes or rain directly. The water collected is mainly used for gardening purposes. The second type is a direct-pumped system. Here a pump is used to direct the harvested rainwater from the underground tanks to the main tank. It can be of two types of suction or submersible. In suction, the harvested rainwater is pumped directly to the main tank, while in a submersible, the water first travels to the underground tank and then to the main tank.

The third type of harvesting system is indirectly pumped water. The water can be stored at any level with the help of a pressure pump. A booster pump is added to the system for regular harvesting. The fourth type of rainwater harvesting is indirect gravity. Here the water harvesting is done with outlets that rely only upon gravity. Here the harvested water is first pumped to a very high-level tank, and from there, the water is supplied with outlets. Due to high gravitational pull, no pump is needed for water distribution. The fifth type of system is entirely dependent on gravity. So, no energy expenditure is required, therefore no use of a pump for harvesting or supplying the harvested water. Here the harvesting tank is made below the gutter level but above the level of the supply outlet. Here gravity is used as efficient and sole energy for harvesting. 

The sixth type of rainwater harvesting is retention ponds. It is one of the most ancient systems used; it has been used for centuries and is very cost-efficient. A pond or lake is used to collect the rainwater naturally over some time. When the collection is completed, the water is treated traditionally to convert it into potable water. The methods are traditional. Firstly, the water is allowed to stand, and all the insoluble materials are scraped off its surface by flocculation, then sedimentation and decantation followed by filtration filters the water. Once the insoluble materials are removed, the water is chemically treated and pumped as potable water.

The seventh and last type of rainwater harvesting system is in-ground storage; it is prevalent in the regions where the rainfall occurs once a year. The underground tank used in this type of harvesting has a shallow evaporation rate and is insulated. Even if this system is used in regions with freezing temperatures, the water will not freeze and has a more significant advantage over the standard tanks. The insulated tanks are attached with outlets and a pump for the supply.

Advantages and Disadvantages of Rainwater Harvesting

Rainwater harvesting comes with advantages and disadvantages.

The advantages of rainwater harvesting are reduction in water bills, suitable for irrigation, ease to maintain and reduced demand for groundwater. Rainwater harvesting system is a one-time investment that will significantly reduce the water bill monthly. Moreover, the set-up cost is far lower than any type of purifier. It is easy to maintain the system; no external water connection is required, nor does any water source have to be connected. It uses the most precious natural source. Rainwater is usually toxicant free, making it perfect for irrigation; if a region has no river or canals, the people can quickly harvest the rainwater and use it for agricultural pursuits. It also reduces the stress on surface water as it is portable and can be used. 

Rainwater harvesting has some drawbacks too, which cannot be overlooked at any cost because, at times, it can pose a significant threat. The first and foremost drawback is the limitation in the capacity of the tank after the tank is complete. Therefore, we cannot store water even if it continues to rain. The second drawback is drought. If there is no rainfall in a region, we cannot harvest it; we must opt for another option that will cost us extra.

Another disadvantage is the high maintenance cost; as the underground system is more prone to pests, they need to be appropriately maintained. Again, not all regions receive water; desert areas are barren and cannot withstand rainwater harvesting systems. Another disadvantage is the contamination of the water as it runs off the surface.

Rainwater Harvesting and the Environment

Rainwater harvesting is essential because it helps in the conservation of water. As we know, freshwater is limited on our planet, rainwater accounts for the renewable source of freshwater. If it touches the ground, the rainwater becomes contaminated and is no longer potable. Thus, they need to be filtered, which will be of high cost; in the regions where the freshwater is limited, rainwater harvesting is the only source of renewable potable water. This method is good for the environment as it reduces the stress upon surface water in a region.

Conclusion

Water harvesting is done mainly in the rain deficit regions of the world to use the stored water annually or during water scarcity. Water plays a significant role in the life of all living organisms since it is a valuable natural resource. Different designs of the system have various benefits in a rainwater harvesting system. Rainwater harvesting comes with advantages and disadvantages. Harvesting rainwater adequately can address the problem of the water crisis worldwide and is environmentally friendly. This simple method can put forward an excellent solution in areas with enough rainfall but insufficient groundwater supply for water conservation.