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Plants that Clean Water

Most of us have learned as children that plants help clean the air. One of the hazards of deforestation is air pollution. But did you know that plants also play a part in cleaning our water? As with air, plants that live on and in the water absorb carbon dioxide and expel oxygen. In aquatic environments, this is helpful to fish and improves water quality. Plants in aquatic systems also absorb nutrients, bacteria, metals, and chemicals.

Plant-based water filtration is getting a lot of attention lately as a sustainable method for cleaning water without chemicals. In 2013 an Oxford University student, Stephan Goodwin Honan, won an international award for his model of a plant filtration system that removes arsenic from water.

irises by water

Cleaning Water With Moss

With this natural way of water filtration getting attention as a way of sustainability, a number of recent studies have looked into the role different plants could have on remediation, or the removal of dangerous substances.

For Instance moss, not having a root system, absorbs water and nutrients throughout the entire plant. In 2017, Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) in Japan published a study which showed Funaria hygrometrica, a certain type of moss, can absorb a large amount of lead due to a special kind of acid in its cell walls.

Later that year, a research group at Stockholm University in Sweden conducted a similar study showing that an aquatic moss, called Warnstofia fluitans can help remove arsenic from water. It grows in Swedish wetlands contaminated with the toxic arsenic from nearby mining operations. The study found that thanks to the moss, the waters arsenic levels dropped 80% in under an hour. Instead of being absorbed by the plant, the arsenic was bound to the plants tissue, making the water safer for humans and animals alike.

cattail

Pine Tree Water Filter

Another model, based on a MIT research team used xylem in pine to filter bacteria from the water. Xylem is the porous sapwood that takes water from the roots of the tree up towards the leaves. The xylem acts as a natural filtration system for the tree. Using sections of pine branches that had been stripped of their bark the researchers added a piece of plastic to the end of the branch. The dirty water flows through the branch where the natural system removes bacteria and sediment from the water.

soft rush

Plants That Filter Water

Heavy metals, bacteria, oil and other pollutants can be removed with the help of wetland plants. Cattail, typically growing between 5 and 10 feet tall, can remove metals such as zinc, cadmium, lead and nitrate from water. Water mint, or Mentha aquatica, grows up to 6 inches high with light purple flowers and should be first planted in a container before being moved to the water. Once it is, water mint can help clean water by removing bacterias like E. coli and Salmonella. Soft rush, or Juncus Effusus is a grass like aquatic plant that grows up to 3 ½ feet high. Washington State University Extension states that in addition to bacteria and oil, Soft Rush also removes heavy metals such as zinc, copper and cobalt from the water.

You can make a pond garden in your yard that filters water. Water lilies and iris’s are two great pond plants that also filter water. Water lilies have proven especially effective in absorbing heavy metals from the water. They also provide shade for fish and help to reduce algae growth. Submerged plants that grow under the water are very good at absorbing pollutants. They will also oxygenate the water and keep fish healthy. Cabomba and hornwort are two good submerged species to plant. The water in your pond can be a great source of an emergency water supply so it’s important that it be clean and healthy

Remember, plants do much more than filtrate our air supply, plants also play a huge role in keeping water clean by absorbing carbon dioxide and expelling oxygen. Whether it is xylem, iris’s or lilies, water can be and is filtered by plant life!


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Plants that Clean Water
Collage of water plants with text, "Plants that Clean Water"

20 Comments

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  1. This is kind of awesome. My friend and I are doing a project on clean water, and are supposed to take action. I’m thinking we do something related to this?

    • I thank you for trying this project. You are never too old to appreciate any attempts to protect this beautiful planet we live on. Go for it!

  2. Hello:

    I’m curious about all these various plants that clean/filter water naturally.
    Can they survive in hotter climates like say New Mexico, Texas, Arizona, etc
    ‘or do they require more moderate temps?

    Thanks mucch,

    Mark

    • Yes, it’s very possible to grow these plants and many other trees. I live in El Paso, TX and have two fully grown pine tree’s in my yard, a Chinese Pistache, Julia Child Roses, wild desert roses, and a few other that were here from the previous owner yet to be named.

  3. Thank you so much for the article. I’m interested in learning a lot more on the subject. I have a small garden, and I am interested in purifying my kitchen waste water into garden water. Where can I find more information on how to do that? Is there a way to remove the soap?

    • Hi Monica, each municipality has different rules and regulations on water recycling, recapturing, and reuse. You will also want to look at what native plants will help you in your garden endeavors. The best place to start is with your local extension office and they should be able to direct you to any local municipalities for rules and regulations.

  4. I love moss. Always wanted a moss garden like the Japanese have. Now I have one in my back garden for past couple of years. Not much of a lawn gal, I have moss growing where the grass doesn’t want to, and the moss beds look like little pools of algae in my lawn. So soft to the touch, they are now sprouting new growth for the Spring that looks like little fronds, so different from mature moss. My friend is setting up a frog terrarium, and I have offered him some of my moss. He will be delighted to learn that moss filters bad chemicals in water.

  5. Hi I love this idea, I am considering how or what I could put in my horses water troughs to clean the water. They are automatic filling, with about 30 liters a day going through them. I definitely know there is too much iron in the water. Would like to remove any other tcms and toxins. What would be a good option?

    • Hi Ruth, keeping algae out of horse water can be difficult but it is important, some people have added algae eating fish to help with this. As far as plants that kill or reduce algae typically it is a plant that covers the surface of the water blocking sunlight and submerged plants that release oxygen. You might want to start by talking to a fish tank and pond expert and then see if the plants they recommend are okay for horses.

  6. A few months later, a group at Stockholm University in Sweden published another pollution-eating moss study, this one demonstrating that the aquatic moss Warnstofia fluitans can remove arsenic from water with astonishing speed, showing an 80 percent decline in arsenic levels from a container of water in less than an hour. Over 90 percent of the arsenic taken up was bound firmly to the moss tissue.

  7. I have two Creek’s running through my yard. I water my animals with creek water do to the chemicals used in tap water. What plants could I use to keep or make the water cleaner for the fur babies. I have seen cattails here in east tenn. Are there others in this area in which I can use

    • Hi Suzanne, we recommend visiting your local agricultural extension office to get more information on water-cleaning plants that are native to your area. They’ll be able to best direct you on which native plants will help you achieve your goals.

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  9. hi i am doing a repackaging project and was wondering if any of these plants could be used as a water container without putting harmful things in the water could yo help me?

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