In this guide, we look at the pros and cons of rainwater harvesting/collection.
Summary – Pros & Cons Of Rainwater Harvesting/Collection
Rainwater harvesting can be done on the individual level, or on the larger scale level commercially, and even in sectors like agriculture (for irrigation), and in dams.
Rainwater collection has several pros.
Among some of them are diversifying a water supply, and also providing an independent and renewable water supply. Rainwater can also be used for different uses, and can be used directly for these uses, or even stored or used for recharging groundwater aquifers.
Rainwater collection is already used widely in many countries around the world.
However, rainwater collection does have potential drawbacks too.
Some of those drawbacks are that it isn’t a suitable water supply method everywhere (especially in hotter and drier climates with low rainfall), as well as there still being costs involved, and sometimes health concerns (and even regulatory/legislative barriers).
Overall, it depends on where and how rainwater collection systems are set up, what they are being used for, as well as several others variables as to whether or not they are suitable and effective.
Pros Of Rainwater Harvesting/Collection
Is Simple Compared To Some Other Water Sources – small and basic setups are simple compared to complex desalination or water recycling setups. Although, some bigger rainwater harvesting systems can require advanced setup and installation – requiring filters, storage containers, pressurization, pumps, treatment devices, and filtration equipment)
Can Be Done On An Individual, Or Large Scale Level – tanks and systems can be made for either small scale or large scale collection. Large dams are technically a form of rainwater collection.
Collected Rainwater Has A Number of Uses – such as irrigation, and with proper treatment – drinking, and different domestic and commercial or industrial uses. It can also be redirected to aquifers as a form of groundwater recharge. Different governments have different regulations and guidelines for rainwater harvesting – some governments ban it outright.
Provides An Independent Water Supply – anyone has access to the rain as long as the climate within a particular area has a wet season, and is not experiencing an extreme climate event like a drought.
Diversifies Water Supply – adding rainwater to a water supply diversifies it from public supply sources, and provides more water security in times of water stress or scarcity.
Can Supplement Other Water Sources – in addition to diversifying water supply, rainwater can be supplemental to other water sources in the event there is a problem with other water sources, or when a drought hits (i.e. rainwater can be stored for when it is needed.
Rainwater Is Renewable – rain is part of the hydrological cycle. This means rain water that is collected and used can continually be collected and used as long as the climate permits it (i.e. there’s no droughts or other weather events impeding it).
Rainwater Can Be Collected In A Number Of Ways – can be collected from roofs, but can also be collected from freestanding objects too. Freshwater flooded forests can also contribute to rainwater harvesting. Even solar panels are now being used for rainwater harvesting (wikipedia.org). There’s many different ways to collect, store and use rainwater.
Can Address Water Quantity & Water Quality Related Issues 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). This can help address issues like water scarcity, water stress, and reduce the incidence rates of water restrictions and water shortages.
Many Countries Are Already Implementing It In Some Way – worldwide, many countries are have several forms of rainwater harvesting set up and operating. In places like Thailand, some of the largest concentrations self supply rainwater harvesting are already set up.
Good For Rural Areas & Developing Countries – rainwater is accessible to demographics that may have challenges receiving water from some other sources of water supply.
Can Help Save Money – after set up costs have had a chance to average out, rainwater systems can sometimes help save money compared to what would have been paid by withdrawing and using from the public supply. You’re essentially saving water and water bills from the public supply.
Can Help Save Energy – in some instances where systems that catch water directly from the sky can then use the water without a pump.
Can Decrease Stormwater Runoff – which as a result decreases loads on public stormwater systems, and can help decrease flooding. It should be noted though that rainwater collection is different to stormwater collection.
Cons Of Rainwater Harvesting/Collection
Isn’t Suitable Everywhere – for example, hot dry climates may not have enough rainwater, or any rainwater at all to collect. There can also be challenges siting rainwater collection close to heavily population areas that need it. Additionally, sometimes is can be difficult in some locations to harvest sufficient quantities of water that can be directed to an end use.
There’s Still Costs Involved – set up/installation is the first. But, once in operation – there’s maintenance and cleaning costs, and electricity costs if a pump 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 Expensive, & Energy Intensive – such as for commercial, industrial or certain types of agricultural uses, and public infrastructure. Only organisations and governments might be able to fund them.
Some Forms Of Rainwater Collection Can Have Contamination Risks – such as collection from some types of roofs that might contain lead, animal feces, and other chemicals and substances. Freestanding rainwater collection straight from the sky might present less contamination risks.
Can Have Other Health Concerns – there can sometimes be concerns with pathogens and other harmful things (pesticides, dusts, particulates, and so on) in the water if it’s not treated or filtered (with a sediment filter), purified or disinfected properly. For drinking water, a high intensity UV sterilizer may be required to make the water suitable for drinking.
Can Overfill – in times of heavy rain, and may flood the immediate area if excess water doesn’t direct to waste properly.
Can Be Problems With Certain Types Of Tanks & Systems – for example, some types of metal tanks may leach chemicals into the rainwater, and some types of underground tanks may eventually crack with ground movement. Other examples of issues can be that some plastic tanks may have fittings that leak, or the plastic can absorb heat. Other tanks may need special liners, and some tanks may be expensive to make and install.
In Urban Areas, Professional Expertise May Be Needed For Installation – 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 good rainwater systems may include.
Legislative Or Regulatory Barriers In Some Places – some governments outright ban rainwater collection, whilst there can be some ambiguity in the regulations or laws surrounding it in other places.