MEEF - Recycling Technologies - Water Recycling
What Is Water Recycling?
Experience at Koele Golf Course, on the Island of Lanai, has
used recycled water for irrigation since 1994. The pond shown is
recycled water, as is all the water used to irrigate this
world-class golf course in the state of Hawaii.
Recycle: verb 1.a. To recover useful materials
from garbage or waste, b. To extract and reuse.
While recycling is a term generally applied to aluminum cans,
glass bottles, and newspapers, water can be recycled as well.
Water recycling is reusing treated wastewater for beneficial
purposes such as agricultural and landscape irrigation,
industrial processes, toilet flushing, and replenishing a ground
water basin (referred to as ground water recharge). Water is
sometimes recycled and reused onsite; for example, when an
industrial facility recycles water used for cooling processes. A
common type of recycled water is water that has been reclaimed
from municipal wastewater, or sewage. The term water recycling
is generally used synonymously with water reclamation and water
Through the natural water cycle, the earth has recycled and
reused water for millions of years. Water recycling, though,
generally refers to projects that use technology to speed up
these natural processes. Water recycling is often characterized
as "unplanned" or "planned." A common example of unplanned water
recycling occurs when cities draw their water supplies from
rivers, such as the Colorado River and the Mississippi River,
that receive wastewater discharges upstream from those cities.
Water from these rivers has been reused, treated, and piped into
the water supply a number of times before the last downstream
user withdraws the water. Planned projects are those that are
developed with the goal of beneficially reusing a recycled water
The Palo Verde Nuclear Generating
Station, located near Phoenix Arizona, uses recycled water for
How Can Recycled
Water Benefit Us?
Recycled water can satisfy most water demands, as long as it is
adequately treated to ensure water quality appropriate for the
use. Figure 1 shows types of treatment processes and suggested
uses at each level of treatment. In uses where there is a
greater chance of human exposure to the water, more treatment is
required. As for any water source that is not properly treated,
health problems could arise from drinking or being exposed to
recycled water if it contains disease-causing organisms or other
Figure 1: While there are some
exceptions, wastewater in the United States is generally
required to be treated to the secondary level. Some uses are
recommended at this level, but many common uses of recycled
water such as landscape irrigation generally require further
The US Environmental Protection Agency regulates many aspects of
wastewater treatment and drinking water quality, and the
majority of states in the US have established criteria or
guidelines for the beneficial use of recycled water. In
addition, in 2004, EPA developed a technical document entitled
"Guidelines for Water Reuse," which contains such information as
a summary of state requirements, and guidelines for the
treatment and uses of recycled water. State and Federal
regulatory oversight has successfully provided a framework to
ensure the safety of the many water recycling projects that have
been developed in the United States.
Irvine Ranch Water District provides recycled water for toilet
flushing in high rise buildings in Irvine, California. For new
buildings over seven stories, the additional cost of providing a
dual system added only 9% to the cost of plumbing.
Recycled water is most commonly used for nonpotable (not for
drinking) purposes, such as agriculture, landscape, public
parks, and golf course irrigation. Other nonpotable applications
include cooling water for power plants and oil refineries,
industrial process water for such facilities as paper mills and
carpet dyers, toilet flushing, dust control, construction
activities, concrete mixing, and artificial lakes.
Although most water recycling projects have been developed to
meet nonpotable water demands, a number of projects use recycled
water indirectly1 for potable purposes. These
projects include recharging ground water aquifers and augmenting
surface water reservoirs with recycled water. In ground water
recharge projects, recycled water can be spread or injected into
ground water aquifers to augment ground water supplies, and to
prevent salt water intrusion in coastal areas. For example,
since 1976, the Water Factory 21 Direct Injection Project,
located in Orange County, California, has been injecting highly
treated recycled water into the aquifer to prevent salt water
intrusion, while augmenting the potable ground water supply.
1Indirect potable reuse refers to projects that
discharge recycled water to a water body before reuse. Direct
potable reuse is the use of recycled water for drinking purposes
directly after treatment. While direct potable reuse has been
safely used in Namibia (Africa), it is not a generally accepted
practice in the US.
While numerous successful ground water recharge projects have
been operated for many years, planned augmentation of surface
water reservoirs has been less common. However, there are some
existing projects and others in the planning stages. For
example, since 1978, the upper Occoquan Sewage Authority has
been discharging recycled water into a stream above Occoquan
Reservoir, a potable water supply source for Fairfax County,
Virginia. In San Diego, California, the Water Repurification
Project is currently being planned to augment a drinking water
reservoir with 20,000 acre-feet per year of advanced treated
What are the Environmental Benefits of Water Recycling?
For over 35 years, in the Montebello
Forebay Ground Water Recharge Project, recycled water has been
applied to the Rio Hondo spreading grounds to recharge a potable
ground water aquifer in south-central Los Angeles County.
In addition to providing a dependable, locally-controlled water
supply, water recycling provides tremendous environmental
benefits. By providing an additional source of water, water
recycling can help us find ways to decrease the diversion of
water from sensitive ecosystems. Other benefits include
decreasing wastewater discharges and reducing and preventing
pollution. Recycled water can also be used to create or enhance
wetlands and riparian habitats.
Water recycling can decrease diversion of freshwater from
Plants, wildlife, and fish depend on sufficient water flows to
their habitats to live and reproduce. The lack of adequate flow,
as a result of diversion for agricultural, urban, and industrial
purposes, can cause deterioration of water quality and ecosystem
health. Water users can supplement their demands by using
recycled water, which can free considerable amounts of water for
the environment and increase flows to vital ecosystems.
Water recycling decreases discharge to sensitive water bodies.
In California, Mono Lake's water
quality and natural resources were progressively declining
from lack of stream flow. In 1994, the Los Angeles
Department of Water and Power was required to stop diverting
one-fifth of the water it historically exported from the
basin. The development of water recycling projects in Los
Angeles has provided a way to partially offset the loss of
Mono Basin water, and to allow the restoration of Mono Lake
to move ahead. Copyright 1994, Mono Lake Committee.
In some cases, the impetus for water recycling comes not from a
water supply need, but from a need to eliminate or decrease
wastewater discharge to the ocean, an estuary, or a stream. For
example, high volumes of treated wastewater discharged from the
San Jose/Santa Clara Water Pollution Control Plant into the
south San Francisco Bay threatened the area's natural salt water
marsh. In response, a $140 million recycling project was
completed in 1997. The South Bay Water Recycling Program has the
capacity to provide 21 million gallons per day of recycled water
for use in irrigation and industry. By avoiding the conversion
of salt water marsh to brackish marsh, the habitat for two
endangered species can be protected.
Recycled water may be used to create or enhance wetlands and
riparian (stream) habitats.
Wetlands provide many benefits, which include wildlife and
wildfowl habitat, water quality improvement, flood diminishment,
and fisheries breeding grounds. For streams that have been
impaired or dried from water diversion, water flow can be
augmented with recycled water to sustain and improve the aquatic
and wildlife habitat.
Water recycling can reduce and prevent pollution.
Incline Village, Nevada, uses a
constructed wetland to dispose of wastewater effluent,
expand the existing wetland habitat for wildlife, and
provide an educational experience for visitors.
When pollutant discharges to oceans, rivers, and other water
bodies are curtailed, the pollutant loadings to these bodies are
decreased. Moreover, in some cases, substances that can be
pollutants when discharged to a body of water can be
beneficially reused for irrigation. For example, recycled water
may contain higher levels of nutrients, such as nitrogen, than
potable water. Application of recycled water for agricultural
and landscape irrigation can provide an additional source of
nutrients and lessen the need to apply synthetic fertilizers.
What Is The Future Of Water Recycling?
Recycled water has been used for a
number of years to irrigate vineyards at California
wineries, and this use is growing. Recently, Gallo Wineries
and the City of Santa Rosa completed facilities for the
irrigation of 350 acres of vineyards with recycled water
from the Santa Rosa Subregional Water Reclamation System.
Water recycling has proven to be effective and successful in
creating a new and reliable water supply, while not compromising
public health. Nonpotable reuse is a widely accepted practice
that will continue to grow. However, in many parts of the United
States, the uses of recycled water are expanding in order to
accommodate the needs of the environment and growing water
supply demands. Advances in wastewater treatment technology and
health studies of indirect potable reuse have led many to
predict that planned indirect potable reuse will soon become
While water recycling is a sustainable approach and can be
cost-effective in the long term, the treatment of wastewater for
reuse and the installation of distribution systems can be
initially expensive compared to such water supply alternatives
as imported water or ground water. Institutional barriers, as
well as varying agency priorities, can make it difficult to
implement water recycling projects. Finally, early in the
planning process, agencies must implement public outreach to
address any concerns and to keep the public involved in the
As water demands and environmental needs grow, water recycling
will play a greater role in our overall water supply. By working
together to overcome obstacles, water recycling, along with
water conservation, can help us to conserve and sustainably
manage our vital water resources.
At West Basin Wastewater Treatment Plant in California,
reverse osmosis, an advanced treatment process, is used to
physically and electrostatically remove impurities from the
More information about water recycling and reuse
U.S. Environmental Protection Agency, Region 9
CWA Standards and Permits Office (WTR-5)
75 Hawthorne Street
San Francisco, CA 94105
U.S. Environmental Protection Agency
Office of Wastewater Management (4204)
Ariel Rios Building
1200 Pennsylvania Ave., NW
Washington, D.C. 20460