Plants That Clean Water

by Jack Grover
waterlily in pond
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If you are looking for a natural and sustainable way to clean water, turn your attention to water-filtering plants. Those plants filter water by absorbing harmful substances and releasing oxygen.

In fact, certain types of aquatic plants have the remarkable ability to absorb toxins, heavy metals, bacteria, and chemicals from water without the need for artificial filtration systems.

From moss to water lilies, hornwort to clover, there are various types of plants that can effectively filter and purify water. These plants help maintain clear and healthy pond water by out-competing algae for nutrients and providing shade.

Nonetheless, it’s important to note that while these plants can effectively filter water for recreational purposes like maintaining ponds or decorative fountains, further testing is necessary before using the filtered water for human consumption or on vegetable crops.

Join us as we delve into the different types of water filtration plants that thrive in various climates.

Types of Water Filtration Plants

First, let’s explore the different types of water filtration plants you can incorporate into your pond to keep the water clean and clear.

Several types of plants are effective in filtering and cleaning water, including oxygenating pond plants, floating pond plants, marginal filter plants, and water lilies.

Oxygenating pond plants like hornwort and water thyme are highly efficient clear water plants. They feed through their roots but also through their foliage.

These plants help to maintain optimal water quality by absorbing excess nutrients from the pond. It’s recommended to use one bunch of these plants for every 3 square feet of surface area in your pond.

Floating pond plants such as water hyacinth and water lettuce are excellent filter plants because they’re heavy feeders and fast growers. These plants float on the water’s surface, providing shade that inhibits algae growth.

Duckweed, fairy moss, ivy leaf duckweed, and floating fern are also effective options for maintaining clear water.

Marginal filter plants like variegated water celery are ideal for low-growing areas around the edges of your pond. When planted in a large mesh basket or shallow gravel bed, these plants grow vigorously and form thick mats of roots.

The variegated foliage adds an attractive touch to your pond while effectively filtering the water.

Water iris is another great choice for a filter plant. Known for its beautiful flowers and sword-like foliage, this plant efficiently filters the water when planted in mesh baskets or shallow gravel beds with ample room for its fibrous root system.

Lastly, water lilies provide more than just aesthetic appeal to your pond. They offer much-needed shade that helps prevent excessive algae growth by blocking out sunlight.


With its impressive height and dense underwater bush, the hornwort is like a superhero for your pond, oxygenating the water and inhibiting the growth of algae. This fantastic oxygenating plant is a favorite among aquarium and pond enthusiasts due to its appealing structure and ease of care.

The hornwort can grow up to 10 feet tall, forming a dense underwater bush in ponds with high nutrient outputs.

The whorled leaves of this plant provide surfaces that benefit healthy microbial communities and protect newly-hatched fish. Its rapid growth rate allows it to take up considerable nutrients from the water column and substrate, making it an efficient cleaner.

Its fragments can persist even when removed from the main plant and become free-floating, allowing for easy propagation through cuttings.

It’s worth noting that mature hornworts may require trimming or restriction to pots as they have weed-like growth tendencies. They are particularly competitive with other submerged plants in still or slow waters, especially in warm temperatures.

Water Iris

The water iris is another plant that guards against nutrient buildup and provides a vibrant touch to the landscape. Its root system plays a crucial role in preventing shore erosion, ensuring your pond’s margins remain intact.

Along with its ornamental value, the water iris also possesses favorable functional qualities that make it an ideal choice for water filtration.

Here are four reasons why the water iris is an excellent plant for cleaning water in ponds:

  1. Nutrient uptake: The high-nutrient concentrations found in fish ponds provide optimal conditions for the growth and survival of water iris seedlings and mature plants. These plants thrive on excess nutrients that have seeped into the substrate, effectively removing them from the water.
  1. Erosion prevention: The emergent stems of the water iris not only add beauty to your pond but also offer protection to newly-hatched fry and other pond visitors as they enter and exit the system. By stabilizing the soil along the margins of your pond, this plant helps prevent erosion.
  1. Colorful display: The decorative effect of densely-planted water irises is truly spectacular. Their stunning blooms bring desirable color to your pond’s surroundings, creating an eye-catching display that enhances its overall aesthetic appeal.
  1. Pollinator attraction: Due to their vibrant flowers, water irises attract various pollinators, such as bees and butterflies. By planting these beautiful blooms around your pond, you can create a habitat that supports local pollinator populations while enjoying their graceful presence.


Cattails thrive in partially submerged environments. These plants, belonging to the Typha species, have unique sausage-shaped inflorescence. You can find them along the edges of freshwater bodies across the Northern Hemisphere.

One fascinating aspect of cattails is their adaptability to varying water levels. Their stems are spongy and capable of transmitting oxygen to their root systems, allowing them to tolerate partial submersion. They spread through rhizomatous growth or by germinating their seeds in muddy substrates.

Cattails have gained recognition for their effectiveness in nutrient removal due to their rapid growth rate. In particular, Typha latifolia, commonly known as bulrush, has shown potential for removing nitrogen and phosphorus from wastewater. This factor makes it a suitable candidate for eco-friendly wastewater remediation methods.

To incorporate cattails into your pond or water filtration system, simply planting a small colony along the margins can provide additional filtration benefits. These resilient plants will help remove excess nutrients from the water while adding beauty and complexity to your aquatic environment.

Water Lilies

Adding vibrant water lilies is one of the best ways to enhance your pond’s beauty and improve water quality.

These plants are popular floating aquatic perennials that offer more than just aesthetic appeal. They play a crucial role in maintaining the clarity of the water column through two main mechanisms.

Firstly, their large lily pads create shade on the surface of the water, which is essential for preventing excessive algal growth.

Algae thrive in sunlight, and when left unchecked, they can cause unsightly blooms that negatively impact water quality. By providing shade, water lilies limit the amount of sunlight reaching the water’s surface and help to control algae growth.

Secondly, water lilies have a remarkable ability to absorb significant amounts of nitrogen and phosphorus-rich compounds from the surrounding environment. These nutrients are often present in excess due to runoff from fertilizers or organic matter decomposition.

By absorbing these compounds into their vegetative parts, water lilies effectively reduce nutrient levels in the pond. It helps maintain a healthy balance and prevent eutrophication, which can result in oxygen depletion and harm aquatic life.

For optimal nutrient removal, it’s crucial to ensure the leaves of your water lilies are in good condition and free from rotting material. Decomposing leaves can release nutrients back into the water column, counteracting their filtering effect.

California Brome

Another way to transform your pond into a vibrant and healthy ecosystem is by introducing California Brome, a versatile grass native to California and the Pacific Northwest. This cool-season perennial bunchgrass has quick-growing fibrous roots, making it incredibly useful for erosion control.

But its benefits go beyond that.

Here are four reasons why California Brome is an excellent choice for improving water quality in your pond:

  1. Absorbs heavy metals: California Brome has the unique ability to absorb heavy metals such as potassium and phosphorus from the water. It helps reduce the levels of these harmful substances, promoting cleaner and healthier water for aquatic life.
  1. Restores degraded areas: This grass is commonly used for restoring spent oil shales, coal mine spoils, heavy metal mine tailings, and roadsides. Its adaptability to various soil conditions makes it an ideal candidate for rehabilitating degraded areas near bodies of water.
  1. Erosion control: With its quick growth and strong fibrous roots, California Brome effectively prevents soil erosion along shorelines or banks of ponds. By stabilizing the soil, it reduces sediment runoff into the water, keeping it clear and free from excess debris.
  1. Native plant species: As a native grass to the region, California Brome is well-adapted to the local climate and ecosystem. It provides essential habitat and food sources for native wildlife while maintaining an ecological balance within your pond.


Moss is a unique plant that doesn’t have roots like most other plants. Instead, it absorbs water and nutrients through its entire body, allowing it to bind large amounts of heavy metals such as lead and arsenic inside its cells.

Studies have shown that certain types of moss, like Warnstofia fluitans, can significantly reduce levels of arsenic in water. This quality makes moss an excellent natural tool for cleaning water and removing harmful contaminants.

In addition to its water-cleaning capabilities, moss is also gaining popularity as an alternative lawn option in wetter climates. Once established, moss is low maintenance and can thrive even in compacted soil with poor nutrients and shade.

With over 12,000 unique species available, there is likely a type of moss that can grow successfully in any situation.

If you’re interested in incorporating moss into your pond or garden, removing it from public areas or nature preserves is ill-advised.

Instead, find a reputable moss nursery. These nurseries propagate moss in sod form and often rescue moss from sites about to be demolished. They can provide guidance on selecting the correct type of moss for your specific needs and teach you how to care for it properly.


Now let’s shift our focus to another plant that plays a role in water filtration: clover.

One of the ways clover helps with water filtration is by preventing soil erosion.

When heavy rains occur, the soil can easily wash away, carrying pollutants and sediments into nearby bodies of water. However, clover’s dense root system helps anchor the soil in place, reducing erosion and allowing the soil to slow down water runoff before it reaches the pond.

Another advantage of clover is its ability to fix atmospheric nitrogen in the soil. It can convert nitrogen gas from the air into a form that plants can use as a nutrient.

This way, clover lowers or eliminates the need for additional nitrogen fertilizer applications on lawns or gardens, reducing the potential runoff of excess nutrients into nearby water sources.

You have several options to incorporate clover into your lawn or garden for improved water filtration.

One popular species is the Dutch white clover, which grows low to the ground and produces small flowers in various colors.

Conversely, micro clover has smaller leaves and fewer flowers when mowed, making it an excellent choice for those looking for a lawn alternative.

Final Thoughts

In conclusion, many plants have the ability to filter water by absorbing harmful substances and releasing oxygen. Planting a few can help you keep your pond crystal clear all year round.

Aquatic plants, such as moss, pine trees, wetland plants, water lilies, and submerged plants, can remove toxins, heavy metals, bacteria, and chemicals from water without the need for chemicals. On top of that, they can even thrive in hotter climates like New Mexico, Texas, and Arizona.

Still, it’s important to remember that water filtered by these plants may not be safe for human consumption or use on vegetable crops without proper testing.

Frequently Asked Questions

How does hornwort contribute to water filtration?

Hornwort contributes to water filtration by acting as an oxygenating plant that inhibits the growth of phytoplankton and algae. It forms dense underwater bushes, which help maintain clear and healthy water in ponds.

What are the benefits of using a water iris for water filtration?

Water iris is a beneficial plant for water filtration because it helps improve water quality and prevents erosion. It thrives in nutrient-rich environments and slightly acidic substrates, making it a compelling choice for maintaining clean and healthy water.

How do cattails help in filtering water?

Cattails help filter water by absorbing excess nutrients like nitrogen and phosphorus. They also act as natural biofilters, removing heavy metals, bacteria, and oil from the water. Plus, their root systems provide stability and prevent soil erosion.

Can water lilies effectively clean water?

Yes, they can. These plants provide shade to prevent algae growth and absorb nitrogen and phosphorus compounds, reducing nutrient levels. Their roots filter out impurities, making the water cleaner and healthier for aquatic life.

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