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Mother
Nature has been recycling our wastewater for millions
of years through a long process of sedimentation, organic
consumption, natural filtration, and disinfection. Modern
technology in the wastewater industry essentially accelerates
Mother Nature’s cleansing process using sedimentation,
oxygenation, filtration, and disinfection.
Recycled water is wastewater
that has been processed through modern primary, secondary,
and tertiary treatment for beneficial reuse following
the strict standards of the California State Department
of Health Services. According to these standards, tertiary-treated
recycled water is safe for all human contact, except drinking.
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Why
recycle water?
History
of recycled water
What is
recycled water used for?
Is it safe?
Where else
is it used? |
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Water
is a precious natural resource that is in short supply
in California. Population increases and efforts to protect
the environment have reduced the reliability of our water
supply. Without widespread development of additional water
resources, the State Department of Water Resources predicts
that by the year 2020, Californians will be short 7 million
acre-feet of water per year during a drought and 2.9 million
acre-feet in an average year. An acre-foot of water is
enough to supply two families for a year. Water reuse
projects, such as Clean Water Revival-Puttin’ on
the Green, are essential to the water resources management
of the region.
Water recycling, practiced for decades in the arid regions
of the United States, is becoming more and more common
throughout California. Dublin San Ramon Services District
has joined hundreds of other agencies statewide in an
effort to help better manage our water resources through
recycling. State law now requires the use of recycled
water if it is available and reasonably priced. Nevertheless,
potential customers look forward to using recycled water
for many more reasons: |
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Recycled
water is reliable – Even
in times of drought when restrictions are placed
on the use of potable (drinking) water for non-essential
uses like landscape irrigation, recycled water is
readily available. During periods of mandatory cutbacks
and water rationing, recycled water can save an
investment of hundreds of thousands of dollars worth
of landscaping. |
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Recycled
water is competitively priced – The
potential cost saving of eliminating disposal fees
by recycling wastewater enables the District to
price the water competitively without increasing
the rates of existing customers. |
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Recycled
water’s nutrients reduce fertilizer costs
– Some harmless nutrients survive the wastewater
treatment process, giving recycled water an added
benefit. Caltrans, for example, has discovered that
its fertilizer costs are reduced for landscaping
along freeways irrigated with recycled water. |
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| HISTORY OF RECYCLED
WATER |
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Recycled
water has been used throughout the State of California
as far back as the turn of the century. The founders of
Golden Gate Park began irrigating with untreated sewage
in 1889 to make the park soil more productive. The first
water reclamation plant was constructed there in 1932.
The City and County of San Francisco continue today to
include water reuse in their master plan for water resources
management. Meanwhile, hundreds of other water and wastewater
agencies also are actively reclaiming our state’s
“liquid gold.” |
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| WHAT IS RECYCLED
WATER USED FOR? |
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Recycled
water most often has been used for irrigation of pastures
and food crops, as well as landscape irrigation of school
grounds, parks and golf courses. More recently, however,
recycled water also has been used for recreation purposes,
habitat restoration, and commercial uses such as carpet
dyeing, paper production, heating and cooling. Purified
recycled water has also been used to help replenish groundwater
supplies, but at DSRSD we only use it for landscape irrigation. |
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| IS RECYCLED WATER
SAFE? |
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The
California State Department of Health Services has set
strict standards, contained in Title 22 of the California
Code of Regulations, for recycled water use.
The tertiary-treated
recycled water produced by DSRSD meets the standards that
allow it to be used for most non-drinking purposes. In
addition, the Regional Water Quality Control Board and
State Department of Health Services have strict permitting
procedures to ensure the reliability of treatment processes
and controlled use of recycled water.
As the potential for
human contact with recycled water increases, Title 22
requires a higher level of treatment and reliability.
Recycled wastewater undergoes primary, secondary and tertiary
treatment at water reclamation plants. During primary
treatment, large solids are removed. Secondary treatment
uses bacteria to remove approximately 90% to 95% of the
remaining solids and uses a disinfectant, such as chlorine,
to destroy bacteria, viruses, and other pathogens. For
many reuse applications, advanced tertiary treatment processes,
such as filtration or reverse osmosis, are required. The
treatment processes duplicate and accelerate nature’s
own purifying actions.
Disinfected tertiary-treated
recycled water is virtually free from all pathogens, including
viruses. Several long-term microbiological studies of
viruses in tertiary-treated recycled water have been conducted.
These studies confirm the absence of pathogens in thousands
of tertiary-treated recycled water samples. For years,
recycled water has safely been used on public facilities
such as school grounds, athletic fields, golf courses,
parks and common areas of residential neighborhoods. There
has never been an incident suggesting even a hint of concern
about the health effects of recycled water use.
Further standards have
been set for recycled water that will be used for indirect
potable reuse applications such as groundwater recharge.
Regulation of groundwater recharge in California is the
jurisdiction of the Department of Health Services and
the State Water Resources Control Board in conjunction
with the Regional Water Quality Control Boards. The DHS
has the responsibility and authority to establish public
health criteria for groundwater usage. In responding to
that role, the DHS has established guidelines for design
and operation of recycled water systems and reviews all
proposals and plans for such projects throughout the state
to ensure the public's health and safety. |
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| WHERE ELSE IS
IT USED? |
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The
California State Legislature has adopted goals for water
recycling that include providing for at least 1.5 million
acre-feet per year of recycled water by the year 2020.
Joining over 200 other water agencies throughout California,
Dublin San Ramon Services District has embarked on a water
recycling program to help meet that goal. Recycled water
is a safe and reliable resource for irrigation and other
uses, and with appropriate treatment, can replenish potable
water supplies such as rivers, groundwater basins, and
reservoirs.
Many communities in
the Bay Area use recycled water for irrigation of pastures
and food crops, as well as landscape irrigation of schools,
parks, and golf courses. In addition, recycled water can
be used for recreation, habitat restoration and commercial
uses such as carpet dyeing, paper production, heating
and cooling.
Bay Area Water Agencies
with Recycled Water Projects include: |
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Marin
Municipal Water District |
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Livermore
Water Reclamation Plant |
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City
of Palo Alto Regional Water Quality Control Plant |
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South
Bay Water Recycling Project (San Jose and Santa
Clara) |
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Central
Contra Costa Sanitation District |
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Carmel
Valley County Sanitation District Zone 1 |
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Monterey
Regional Water Pollution Control Authority |
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Carmel
Area Wastewater District |
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Many
other communities across the nation have implemented projects
to use purified recycled water to supplement drinking
water supplies. Some communities use reverse osmosis and
others use less advanced technologies. Here are some examples: |
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Delta
Diablo Sanitation District – This recycled
water facility is the largest industrial recycled
water project in the state of California. It provides
up to 8,600 acre feet/year of tertiary treated recycled
water to two power plants and 20 acres of parks
and landscaped areas. |
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Orange
County, California – The Orange County
Water District currently injects recycled water
into depleted groundwater basins. |
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West
Basin Water District – The West Basin
Water District uses microfiltration, reverse osmosis
and ultraviolet light technologies to treat recycled
water for groundwater injection. A neighboring water
district, the Water Replenishment District of Southern
California, has been inspired to construct a similar
water treatment facility. |
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Scottsdale,
Arizona – The City of Scottdale's new
wastewater treatment plant uses microfiltration
and reverse osmosis to purify treated wastewater
before it is injected into the groundwater basin. |
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Los
Angeles County – Treated wastewater
runs through dual media filters at the Montebello
Forebay Groundwater Recharge Project and is discharged
into the Rio Hondo River. This water is diverted
to the groundwater basins. The reclaimed water constitutes
18.7 percent of the groundwater supply, on average. |
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Reno,
Nevada – The Tahoe-Truckee Sanitation
Agency Water Reclamation Plant combines conventional
activated sludge secondary treatment with biological
phosphorus removal to treat the wastewater. The
treated water is released into the Truckee River
which is the source of the City of Reno’s water
supply. |
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Northern
Virginia – The Upper Occuquan Sewage
Authority reclaims wastewater before discharging
it into the Occoquan Reservoir. This reservoir is
an important source of drinking water for about
one million people in Northern Virginia. |
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El
Paso, Texas – The Fred Hervey Water
Reclamation Plant recovers and treats wastewater
which is then recharged into the groundwater. The
water eventually travels to one of El Paso’s
potable water fields to become part of the drinking
water supply. |
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Suburban
Dallas – The North Texas Municipal Water
District operates a wastewater treatment plant known
as Wilson Creek. Treated wastewater is discharged
into a stream that is the tributary to Lake Levon,
the water supply for the entire district. |
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Las
Vegas, Nevada – Since the 1950s secondary
treated wastewater has been discharged into the
Las Vegas wash. The wash is located between the
Las Vegas Valley and Lake Mead and represents two
percent of the flow into Lake Mead. Lake Mead is
the primary drinking water source for the Las Vegas
Valley. |
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Atlanta,
Georgia – The Clayton County Sanitation
District operates a water treatment facility that
discharges to forested land with runoff flowing
to Pates Creek. Pates Creek is one of three creeks
that feeds into a reservoir serving Metropolitan
Atlanta. |
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