In this guide, we look at the potential pros and cons of rainwater harvesting & collection.
Summary – Pros & Cons Of Rainwater Harvesting & Collection
Firstly, What Is Rainwater Harvesting & Collection?
We discuss what rainwater harvesting and collection is, and other key aspects in this guide.
Potential Pros
Is Already Used Widely On A Global Level
Some Rainwater Systems Are Simple, & Easy To Set Up & Operate
There’s Different Scales Of Rainwater Collection Available
Rainwater Can Be Stored In A Number Of Ways
Rainwater Has A Number Of Potential Uses
Can Be Used As A Private Supply Of Water
Rainwater Is Renewable
May Help Save Energy
May Have Other Sustainability Benefits
May Help Diversify & Strengthen A Local Water Supply
May Help Address Water Quality In Some Places
May Be Good For Rural Areas, Isolated Areas, & Developing Countries
May Be A Cost Effective Water Source Compared To Other Water Sources In Some Instances
May Have Several Other Social Or Economic Benefits
May Be Used In Emergencies In Some Instances
May Be Used In Conjunction With Stormwater Management Setups
May Help With Building Design & Performance
Potential Cons
Legislative Or Regulatory Restrictions In Some Places
Is Not Practical Or Effective Everywhere
The Variable Nature Of Rainfall, & Several Other Factors Limit The Quantity Of Rainwater That Can Be Collected
There’s Still Costs To Consider
Large Scale Projects Can Be More Energy Intensive
May Be Less Sustainable Than Some Other Forms Of Water Conservation In Some Ways
Some Forms Of Rainwater Collection May Have Contamination & Health Risks To Consider
Professional Expertise May Be Needed For Installation In Some Instances
Specific Types Of Tanks & Systems May Have Their Own Potential Problems To Consider
Overflow May Be A Problem In Some Instances
Potential Pros Of Rainwater Harvesting & Collection
Is Already Used Widely On A Global Level
There’s a range of different forms of rainwater harvesting & collection systems set up in different regions across the world.
Some regions of the world even outright promote or incentivize rainwater harvesting in their government policy or regulations.
Some Rainwater Systems Are Simple, & Easy To Set Up & Operate
For example, some small rainwater collection setups can be simple and easy to set up and operate, requiring only a roof catchment surface, and collection points to transfer water to a storage area (like a tank for example)
This is in comparison to other water sources like desalination or water recycling plants for example, that can involve much more advanced equipment and technology.
Having said this, there are some bigger rainwater harvesting systems that might require advanced setup and installation – requiring filters, storage containers, pressurisation, pumps, treatment devices, and filtration equipment.
So, it depends on the scale and features of the setup.
There’s Different Scales Of Rainwater Collection Available
Smaller scale rainwater collection systems can be setup on the household level.
However, there’s also rainwater harvesting systems that operate at a much larger scale, such as some systems owned by companies or institutions collecting water on the commercial or industrial level.
One example might be some farms collecting larger quantities of rainwater for irrigation.
Rainwater Can Be Stored In A Number Of Ways
For example, rainwater can be stored in both above ground and below ground tanks, pits, cisterns, and more.
Rainwater Has A Number Of Potential Uses
Some regions allow the consumption or drinking of rainwater (which may or may not need some form of treatment first, depending on the setup and local regulations)
Rainwater also has a number of non potable uses too, such as:
– Domestic uses (cooking, cleaning, washing, watering, and so on)
– Irrigation on farms
– Different commercial and industrial uses
– And even groundwater replenishment
Can Be Used As A Private Supply Of Water
The collection of rainwater by private entities (individuals, businesses, etc) is a way to have a separate water supply to the public water supply
Rainwater Is Renewable
Rain is part of the hydrological cycle where water is continuously cycled around Earth.
This means that rainwater is a renewable water source that can continually be collected/harvested as long as it continues to rain (changing rainfall patterns, natural events like droughts, and other factors can impact rainfall).
May Help Save Energy
In some instances, rainwater setups may rely only on gravity to feed water through pipes into a rainwater storage tank.
If there’s no pump using electricity, then rainwater collection and storage may use less energy than some other water supply options.
Some water treatment technology for rainwater collection may use energy though.
May Have Other Sustainability Benefits
A few sustainability benefits might be:
– wikipedia.org indicates that (paraphrased) when doing a lifecycle assessment, the environmental impact of rainwater harvesting depends on the building design and function, but it can help save water, save storm water from entering sewer networks (and the treatment on sewer waste), and sometimes saves environmental emissions
– Rainwater collection systems may have less environmental costs than other water sources such as dams in some instances
May Help Diversify & Strengthen A Local Water Supply
Rainwater harvesting can help diversify a local water supply, by being a water source that is supplemental and complementary to other water sources, such as surface water, ground water, and so on.
For an individual, it also diversifies their water supply from the public supply too.
Diversification may strengthen the local water supply for a number of reasons, including but not limited to being able to add to the total water supply, being able to store rainwater and use it at a later time (such as when rainfall stop), and more.
These things may ultimately help ensure a city’s water security, and protect them against water risks like water stress or water scarcity.
It may also help protect them against a number of other water issues.
May Help Address Water Quality In Some Places
[In India] Chennai had a 50% rise in water level in five years and the water quality significantly improved [since implementing rainwater harvesting] (wikipedia.org).
May Be Good For Rural Areas, Isolated Areas, & Developing Countries
In rural areas and remote/isolate areas where there is a lack of water infrastructure, or a lack of adequate water infrastructure, rainwater collection and harvesting can provide a practical and cost effective water supply option.
May Be A Cost Effective Water Source Compared To Other Water Sources In Some Instances
Rainwater collection and harvesting setups may be cheaper to set up and cheaper to run than some other water supply methods.
This is especially the case for simple rainwater collection setups, or where the rainwater supply method requires little or no energy to operate.
So, the average price of the water supplied may be cheaper than some other water sources.
This may help save money for both individuals, and also public organisations and utilities.
It may also benefit lower income regions, or regions where other sources of water would be costly to set up and operate.
Not only is the initial setup cost cheaper for lower income regions, but, simple systems that require little to no further financial investment or upkeep costs can be a cost effective form of water supply.
May Have Several Other Social Or Economic Benefits
Including but not limited to:
– Reducing the risk of small plot farmers losing harvests in some countries where water scarcity can be an issue
– Decreasing the risks or effects of soil erosion or flooding for small scale agricultural producers in places with hilly or sloping land, or low level land
– Reducing the social costs of alternate water sources like dams in some instances
May Be Used In Emergencies In Some Instances
May Be Used In Conjunction With Stormwater Management Setups
wikipedia.org mentions that (paraphrased), when used with certain technology, stormwater management using detention basins can double as a source of rainwater harvesting
May Help With Building Design & Performance
wikipedia.org indicates that ‘… [in urban areas …] ‘green’ rooftops with rainwater catchments have been found to reduce building temperatures by more than 1.3 degrees Celsius’
Potential Cons Of Rainwater Harvesting & Collection
Legislative Or Regulatory Restrictions In Some Places
Different governments have different regulations and guidelines for rainwater harvesting, collection and use.
Some governments allow it with certain conditions and safety requirements.
Other governments restrict it, or ban it outright.
There can be some ambiguity in the regulations or laws surrounding rainwater collection and use in some places too.
Is Not Practical Or Effective Everywhere
For example, hot and dry climates may not have enough rainfall for rainwater collection to be practical or effective.
Places that are subject to droughts and other natural events may be impractical to collect rainwater in too.
There may also sometimes be challenges in siting rainwater collection close to heavily populated areas that need it.
The Variable Nature Of Rainfall, & Several Other Factors Limit The Quantity Of Rainwater That Can Be Collected
Rainfall is a variable in that rainfall patterns can change, and rainfall from year to year or month to month can be inconsistent.
Some years can be drier that others, and a changing climate or natural events like droughts can impact precipitation levels too.
This local variation impacts how much water can be collected from year to year, or season to season, in a given area.
Additionally, individual rainwater collection systems are limited in the amount of water they can collect, depending on factors like the catchment area size, the amount of storage space available, and so on.
There’s Still Costs To Consider
Firstly, there’s set up and installation costs to consider.
Some larger or more advanced rainwater harvesting setups and equipment can be more expensive, such as some commercial, industrial or agricultural rainwater collection setups.
At the operation stage, there’s maintenance and cleaning costs, and also electricity costs if a pump or even a water filtration, purification or treatment systems is used.
Tanks and systems also have to replaced at some point once they reach the end of their lifespan.
Large Scale Projects Can Be More Energy Intensive
Such as commercial, industrial or certain types of agricultural rainwater collection setups.
This is especially the case if collected rainwater has to be pumped (as pumps use electricity), or, the water has to be pumped longer distances (which requires more energy).
May Be Less Sustainable Than Some Other Forms Of Water Conservation In Some Ways
wikipedia.org notes that The London Olympic Park where rainwater harvesting was used, ‘… rainwater harvesting was a less efficient use of financial resources to increase sustainability than the park’s blackwater recycling program’
Some Forms Of Rainwater Collection May Have Contamination & Health Risks To Consider
For example, roofs that catch rainwater may contain pathogens, animal feces, dust, particulates, metals like lead, and other potentially harmful chemicals and substances.
Pesticides can be found in notable concentrations in rainwater in some regions of the world too.
This may especially be the case if the water is not treated or filtered (with a sediment filter), purified or disinfected properly prior to use.
For drinking water, a high intensity UV sterilizer may be required to make the water suitable for drinking.
Professional Expertise May Be Needed For Installation In Some Instances
To make sure the system is engineered correctly, and features like back flow prevention devices are fitted so the mains water is isolated from the rainwater system.
There’s other requirements and safety features that advanced rainwater systems may include.
This adds a layer of complexity and cost to the rainwater setup.
Specific Types Of Tanks & Systems May Have Their Own Potential Problems To Consider
For example:
– Some types of old metal tanks may leach chemicals into the rainwater
– Some types of underground tanks may eventually crack with ground movement.
-Some plastic tanks may have fittings that leak, or the plastic can absorb heat.
– Some tanks may need special liners
– Some tanks and systems may be expensive to make and install, or to maintain
Overflow May Be A Problem In Some Instances
Heavy rain may sometimes cause tanks or storage areas to overflow, and this may cause flooding or cross contamination issues.
Sources
1. https://en.wikipedia.org/wiki/Rainwater_harvesting
2. https://www.versatiletanks.com.au/the-pros-and-cons-of-rainwater-harvesting/
3. https://greencoast.org/rainwater-harvesting-pros-and-cons/
4. https://www.conserve-energy-future.com/advantages_disadvantages_rainwater_harvesting.php
5. https://www.ecpgroup.com/journal2/blog/post?journal_blog_post_id=69
6. https://www.harryhelmet.com/the-pros-and-cons-of-different-rainwater-harvesting-storage-tanks/
7. https://www.renewableenergyhub.co.uk/main/rainwater-harvesting-information/benefits-of-rainwater-collection/
8. https://byjus.com/biology/rainwater-harvesting/
9. https://www.yourhome.gov.au/water/rainwater
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