Rainwater Harvesting System Definition, Principle, Parts Explained
A rainwater harvesting (RWH) system is a system comprising of components that collect, filter and store rainwater for future use. This article discusses rainwater harvesting system definition, principle and parts, as outlined below;
-Rainwater Harvesting System Definition: 5 Ways to Define Rainwater Harvesting Systems
-How A Rainwater Harvesting System Works
-Parts of a Rainwater Harvesting System
Rainwater Harvesting System Definition: 5 Ways to Define Rainwater Harvesting Systems
Rainwater harvesting system is a tool for improving the sustainability of the ecosystem by reducing the risk of environmental degradation and resource depletion, through the collection and storage of rainwater .
As implied above, the primary objective of rainwater harvesting systems is water conservation. Below is an alternative rainwater harvesting system definition which portrays the concept from an economic perspective;
A rainwater harvesting system is a system which is used for recycling and conservation of natural water resources in a circular economy, thereby reducing energy waste, supporting sustainable development, and boosting productivity .
Some types of rainwater harvesting systems are mentioned in the definition below;
A rainwater harvesting system is a mechanical concept or device used to capture and store rainwater, and which may be either gravity-driven, direct-pumped, or indirect-pumped in its mode of operation .
Below is an alternative rainwater harvesting system definition which lists some important components of the system;
Rainwater harvesting system is a water management system comprising of conduits, funnels, filters, first-flushing equipment, debris traps, and storage vessels for the collection and storage of rainwater.
Lastly, some uses of the system are mentioned in yet another rainwater harvesting system definition below;
Rainwater harvesting system is a device used to collect and store rainwater from rooftops or ground surfaces for any of various purposes such as flood/erosion control, sustainable agriculture, potable water supply, and hydroelectricity generation.
How A Rainwater Harvesting System Works
A rainwater harvesting system works by rainwater collection, filtration, and storage. Each of these is discussed briefly below;
1). Rainwater Collection (as part of the Working Principle of a Rainwater Harvesting System)
Rainwater collection is the first step in the typical operation of a RWH system.
The effectiveness and efficiency of rainwater collection depend on factors like the surface area and symmetry of the catchment (rooftop, pavement, etc.), and the characteristics of the conduits which channel the collected water into the system.
While most rainwater harvesting systems rely on gravity for water flow, some make use of pressure from pumps to improve flow efficiency.
2). Rainwater Filtration
Filtration is generally important as a basic measure to reduce the concentration of contaminants like dust and insoluble particulate matter, in rainwater.
The filtration function could be absent in primitive RWH systems. Others usually are equipped with at least one filter bed. In some integrated systems, reverse osmosis, heat control, and other functionalities could be incorporated .
3). Rainwater Storage (as part of the Working Principle of a Rainwater Harvesting System)
Storage is the final stage in the process of rainwater harvesting.
The storage capacity of a RWH system is determined mainly by the volume of rainwater that is regularly supplied.
Storage could be preceded by filtration, to optimize the quality of water in the system, and broaden its range of possible application.
To address space constraints, storage tanks may be installed overhead or underground.
Water can be subsequently recovered from the storage system for use.
Parts of a Rainwater Harvesting System
Parts of a rainwater harvesting system are; conduits, filter, first-flush, and storage tank.
1). Conduits (as one of the Parts of a Rainwater Harvesting System)
The conduits are simply pipes that help with transport of rainwater from the catchment to the storage vessel.
Rainwater harvesting systems use conduits that may be made from galvanized iron (GI) or polyvinyl chloride (PVC), among other materials .
These materials extend from the catchment (rooftop, pavement, etc.), to the storage tank which could be above-ground or underground.
The design of RWH systems usually aims to reduce the complexity and space-occupancy of conduits by running them along walls and ground surfaces.
Filtration is one of the processes involved in rainwater harvesting.
It is achieved using one or more filter beds; which are usually layers comprising of inert, granular material, that are used to pre-treat rainwater before it enters the storage tank(s).
Materials which could comprise a RWH filter bed include sand and gravel. The coarseness of these materials is decided baser on the nature of impurities in the water, and the level of purification (and purity) which is desired.
3). First-Flush (as one of the Parts of a Rainwater Harvesting System)
A ‘first-flush’ in a rainwater harvesting system is a simple device or component that diverts the first streams of rainwater that are captured by the catchment surface.
The purpose of this component is to remove impurities that could have accumulated on the surface (rooftop, pavement) prior to rainfall, thereby preventing these impurities from contaminating the reserves.
First-flush diverter can help reduce the time and/or money which could be spent on catchment surface-cleaning.
4). Storage Vessel
The storage vessel or tank is the final destination of rainwater that is captured and collected by the system. Reserves are stored in this component.
Occasional cleaning, disinfection and inspection of the storage tank is usually needed.
A rainwater harvesting system is a water conservation system used to collect, filter and store rainwater for future use.
Rainwater harvesting systems work by;
1. Rainwater Collection
2. Rainwater Filtration
3. Rainwater Storage
Parts of a rainwater harvesting system are;
4. Storage Vessel
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