Impact: Is Reverse Osmosis Water Bad for the Environment?
Written by: Gene Fitzgerald // Last Updated: Oct 18, 2023
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Reverse osmosis (RO) is a widely used method for water purification with both positive and negative environmental implications.
On the one hand, it is known to waste water, but when compared to purchasing bottled water, which contributes to plastic pollution and a larger CO2 footprint, RO emerges as a more favorable option.
Industrial applications of RO raise more significant environmental concerns.
Let’s delve into the unintended consequences and overall impact of reverse osmosis to find out: Is reverse osmosis bad for the environment?
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Key Takeaways
- Reverse osmosis has a relatively low recovery ratio, meaning a larger part of the input water gets wasted during the process. This so-called brine needs to be disposed which, when it comes to seawater desalination, poses a problem to aquatic life.
- Reverse osmosis also requires energy input.
- And it may cause mineral deficiencies if not treated with remineralization salts after filtering.
- Despite this, reverse osmosis remains a more environmentally friendly option than drinking bottled water or using a water distiller.
- The environmental impact of home reverse osmosis systems is negligible.
What Are the Unintended Consequences of Reverse Osmosis?
The revolutionary invention of the reverse osmosis membrane has dramatically transformed the global water scene. This technological advancement, which is now more energy-efficient, reliable, and cost-effective than ever, provides clean drinking water to some of the world’s driest cities.
In 2018, about 1% of the world’s population depended on seawater desalinated through this method. It’s estimated that by mid-century, over a billion people could be using water treated via reverse osmosis.
However, there are concerns about the environmental impacts of desalination plants and RO consumption. RO has a low recovery ratio and high energy demand and may cause mineral deficiencies if not treated with remineralization salts after filtering.
Environmental Impact of RO Seawater Desalination
RO desalination, the process of rendering seawater potable, is not without its environmental implications. The method is energy-intensive, significantly contributing to greenhouse gas emissions.
Desalination also yields a byproduct known as brine, a salt-heavy solution that, when reintroduced into the ocean, can detrimentally impact marine life and overall water quality. This brine often contains harmful metals and other substances, posing further environmental risks.
The economic aspect of desalination also presents hurdles, with the process being costly and the management of the leftover brine posing challenges. In fact, for every gallon of freshwater generated, approximately one and a half gallons of brine are produced. Research indicates that improved methods of managing this byproduct are needed to mitigate its environmental and financial toll.
Currently, most of the brine is discarded back into the ocean, posing threats to fish populations, corals, seagrasses, and fish larvae. This concern led California regulators to recently reject a $1.4 billion desalination plant proposal due to the potential harm to marine life, sea level rise and flooding risks, and cost implications.
Though seawater desalination via means of reverse osmosis could prove beneficial in certain circumstances, especially as costs decrease and better brine management methods are developed, experts recommend prioritizing less detrimental solutions. These include water conservation, wastewater reuse, water supply reallocation, and reducing agricultural water usage.
Possible Impact on Nutritional Status of Communities
Reverse osmosis is an incredibly effective water filtration method. It is so effective that it eliminates essential minerals such as magnesium, calcium, and fluoride from water. Theoretically, consuming such ultra-purified water over a long period could lead to health issues, including cardiac disorders and dental decay.
- Post reverse osmosis, water treatment facilities usually reintroduce certain minerals into the water, a process known as remineralization. However, magnesium, which is needed to facilitate multiple chemical processes in the body, isn’t usually included in this process. Consequently, individuals in regions where reverse osmosis is the sole source of water may need to increase their dietary magnesium intake or consider supplements.
- Fluoride also gets removed during reverse osmosis, potentially leading to increased dental issues in communities where fluoride toothpaste usage is low. There are also concerns about the possible absence of other vital nutrients from water treated via reverse osmosis. For instance, some research suggests a correlation between lower levels of lithium in drinking water and elevated suicide rates.
- A further concern with reverse osmosis water is its potential to erode pipes, which could release harmful substances like arsenic, chromium, and lead. This occurs because the highly purified water can dissolve the protective layers within the pipes.
- Another concern is the lack of magnesium in the remineralization step. Despite no observed adverse health effects from magnesium deficiency in populations consuming only remineralized RO water, this issue merits attention.
RO in the Private Sector: Are Home Reverse Osmosis Systems Bad for the Environment?
Home reverse osmosis systems do not substantially contribute to adverse environmental consequences like industrial RO. Modern-day in-home systems have very high recovery ratios, and there are methods by which wastewater can be collected and used for other household tasks, such as car washing.
Regarding the wastewater, which still carries contaminants, these chemicals were already entering the water supply through regular activities such as flushing toilets or doing laundry. The installation of an RO system doesn’t amplify this pollution. The duty to eliminate these chemicals from our water supply falls upon the entities responsible for their existence. To prevent contaminants from getting into the water, you must appropriately dispose of medications and chemicals and watch what you are pouring down your sinks!
Reverse Osmosis vs Bottled Water
There’s a compelling argument for RO over bottled water. The environmental impact of plastic bottles is well-documented, but many may not know that filtered water, like that from RO systems, could be safer than daily usage of disposable bottles. The bottled water industry has faced criticism for its lack of regulation, with companies not required to disclose vital information such as the water source, treatment methods, or contaminant content.
Using an RO water filter is more environmentally friendly than plastic bottles and offers added convenience. Think of all the plastic you will save over a few years.
Further Reading:
Reverse Osmosis Water Purification vs Distillation
Distillation involves heating water into steam and then condensing it back into liquid, while reverse osmosis forces water through a specialized filter to reject impurities.
Energy consumption significantly differs between these processes. On a commercial scale, to produce a ¼ gallon of distilled water, 1.65 kW of power and over 2 gallons of cooling water are required. Generating ¼ gallon of water via reverse osmosis requires less than 0.1 kW and around a gallon of water, making reverse osmosis an environmentally superior choice.
Sources
https://pubs.acs.org/doi/10.1021/acs.est.9b01755
https://pubmed.ncbi.nlm.nih.gov/17671660/
https://www.sciencedirect.com/science/article/pii/S0011916417307750
https://www.cleancapefear.org/dailyfilter/s6ewsjpm7aje65tftgyncldg6sgjbl
If you have any questions about the environmental impacts of reverse osmosis please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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