A Citizen’s Guide to

Phytoremediation

What Is Phytoremediation?

Phytoremediation uses plants to clean up contaminated 

environments. Plants can help clean up many types of 

contaminants including metals, pesticides, explosives, 

and oil. However, they work best where contaminant 

levels are low because high concentrations may limit 

plant growth and take too long to clean up. Plants 

also help prevent wind, rain, and groundwater flow 

from carrying contaminants away from the site to 

surrounding areas or deeper underground.

How Does It Work?

Certain plants are able to remove or break down 

harmful chemicals from the ground when their roots 

take in water and nutrients from the contaminated soil, 

sediment, or groundwater. Plants can help clean up 

contaminants as deep as their roots can reach using 

natural processes to:

• Store the contaminants in the roots, stems, or 

leaves.

• Convert them to less harmful chemicals within 

the plant or, more commonly, the root zone.

• Convert them to vapors, which are released into 

the air.

• Sorb (stick) contaminants onto their roots where 

very small organisms called “microbes” (such 

as bacteria) that live in the soil break down the 

sorbed contaminants to less harmful chemicals. 

(See A Citizen’s Guide to Bioremediation [EPA 

542-F-12-003].)

Phytoremediation often is used to slow the movement 

of contaminated groundwater. Trees act like a pump, 

drawing the groundwater up through their roots to keep 

it from moving. This method of phytoremediation is 

called “hydraulic control.” It reduces the movement of 

contaminated groundwater toward clean areas offsite.

Constructed wetlands are another form of 

phytoremediation. A wetland may be created at a site to 

treat acid mine drainage that flows through it or as a final 

treatment step for water discharged from other treatment 

systems. Water treated with constructed wetlands 

generally has very low concentrations of contaminants 

that need to be removed before it may be discharged 

into a lake or stream. The construction of wetlands may 

involve some excavation or regrading of soil at the site 

in order for water to flow through it without pumping. 

The area is planted with grasses and other vegetation 

typical of naturally occurring wetlands in the area.

Certain plants are better at removing contaminants 

than others. Plants used for phytoremediation must 

be able to tolerate the types and concentrations 

of contaminants present. They also must be able 

to grow and survive in the local climate. Depth of 

contamination is another factor. Small plants like ferns 

and grasses have been used where contamination 

is shallow. Because tree roots grow deeper, trees 

such as poplars and willows are used for hydraulic 

control or to clean up deeper soil contamination and 

contaminated groundwater.

How Long Will It Take?

Phytoremediation may take several years to clean up 

a site. The cleanup time will depend on several factors. 

For example, phytoremediation will take longer where:

• Contaminant concentrations are high.

• The contaminated area is large or deep.

• Plants that have a long growing time are used.

• The growing season is short. 

tree roots take

in water and

contamination

from the ground

contaminated

soil

water

table

contaminated groundwater

water enters tree

where contamination

is cleaned up

clean

soil

vapors
United States Office of Solid Waste and EPA 542-F-12-016

Environmental Protection Emergency Response September 2012

Agency (5102G) www.epa.gov/superfund/sites

www.cluin.org

Example

Phytoremediation is being 

used to clean up contaminated groundwater near a 

former disposal area at the 

Aberdeen Proving Ground 

in Maryland. This area was 

used for disposal and burning 

of industrial and warfare 

chemicals from 1940 through 

the 1970s. Chemicals used 

as industrial degreasers and 

solvents were found to be 

a particular problem in the 

groundwater.

In the spring of 1996, 183 

poplar trees were planted 

in a one-acre area. The 

trees draw in contaminated 

groundwater and break down 

contaminants in the root zone. 

The groundwater levels near 

the trees show that they are 

keeping the plume of contaminants from moving to clean 

areas. EPA estimates that 

within 30 years of the start 

of cleanup, the contaminants 

in groundwater at the site 

may be reduced by up to 85 

percent.

For More Information

For more information about 

this and other technologies in 

the Citizen’s Guide Series, 

visit:

www.cluin.org/remediation

www.cluin.org/products/

citguide

www.cluin.org/phyto

NOTE: This fact sheet is intended solely as general information to the public. It is not intended, nor can it be relied upon, to create any 

rights enforceable by any party in litigation with the United States, or to endorse the use of products or services provided by specific 

vendors. The Agency also reserves the right to change this fact sheet at any time without public notice.

These factors vary from site to site. Plants may have to be replaced if they are 

damaged by extreme weather, pests, or animals. This also will add time to the 

cleanup.

Is Phytoremediation Safe?

Phytoremediation is a low-risk and attractive cleanup method. Fences and 

other barriers are constructed to keep wildlife from feeding on contaminated 

plants. In certain instances, plants may release chemical vapors into the air 

in a process called “phytovolatilization.” When this occurs, workers sample 

the air to make sure the plants are not releasing harmful amounts of vapors.

How Might It Affect Me?

Phytoremediation cleanups cause little disruption to the site or surrounding 

community. Initial work may involve grading or tilling of the soil with earth-moving 

equipment, and backhoes may be needed to plant trees and large shrubs. 

Residents and businesses near the site may hear equipment noise or detect 

an odor if fertilizer is added to the soil. Any airborne dust can be minimized by 

watering down the soil.

Plants used for phytoremediation can make a site more attractive. The use 

of native plants is encouraged since they are better adapted to the area’s 

conditions and less likely to attract nuisance animals or pests.

Why Use Phytoremediation? 

EPA uses phytoremediation for many reasons. It takes advantage of natural plant 

processes and requires less equipment and labor than other methods since 

plants do most of the work. Also, the site can be cleaned up without digging 

up and hauling soil or pumping groundwater, which saves energy. Trees 

and smaller plants used 

in phytoremediation help 

control soil erosion, make 

a site more attractive, 

reduce noise, and improve 

surrounding air quality. 

Phytoremediation has 

been successfully used 

at many sites, including 

at least 10 Superfund 

sites across the country.

Poplar trees at a phytoremediation site.