DECENTRALIZED WASTEWATER
TREATMENT CAN BE
GREEN AND SUSTAINABLE

Decentralized wastewater treatment can
meet the triple bottom line of protecting
the environment, being efficient, and
contributing to community well-being by:

•	increasing water quality and availability,

•	using energy and land wisely,

•	responding to growth while preserving
green space, and

•	using the natural treatment properties of
the soil.

HOW CAN DECENTRALIZED WASTEWATER TREATMENT BE GREEN?

Increasing water quality and
availability - Decentralized
wastewater treatment effectively
and efficiently treats domestic
sewage to protect water
quality and support local water
supplies. The wastewater
from decentralized systems
stays in the local watershed
as it returns to the drain field,
dispersing into the underlying
soil and eventually recharging
groundwater and/or reentering
the local watershed. Advanced
decentralized treatment systems
can achieve treatment leveis
comparable to centralized
wastewater treatment systems
while minimizing the level
of phosphates and nitrogen
entering the ground water.
Discharging to the soil can
further remove contaminants
so as to maintain water quality
Decentralized systems can

be designed to meet specific
treatment goals, to handle
unusual site conditions, and to
address local environmental
protection requirements. Using
decentralized systems may also
make it easier for a community
to employ water reuse
techniques and, as a result,
reduce the demand for treated
drinking water.

Using energy and land
wisely - Most decentralized
systems take advantage of
gravity flow rather than using
energy to pump the wastewater.
Additionally, decentralized
wastewater treatment systems
often incorporate septic tanks at
the wastewater source resulting
in reduced costs and energy
for treatment of septage prior to
land dispersal.

Responding to growth while
preserving green space -

Decentralized systems can be
flexible and scaled to a desired
size or footprint. For example,
decentralized systems can
easily be scaled to a needed
size for communities with rapid
growth and/or where installing
pipelines a long distance to a
central waste facility can be
too expensive. Decentralized
systems can be designed to
meet specific growth goals
through planning where and
how the community will grow.
Decentralized systems tend to
have smali, minimally intrusive
environmental footprints and
often have the benefit of creating
green spaces in communities.

Using the natural treatment
properties of the soil -

Decentralized systems provide
good opportunities to use the
natural environment. They can
help reduce the level of difficulty
and cost to treat pollutants,
such as nutrients, and keeping
them from entering lakes, rivers,
and streams. The soil acts as a
natural filter and provides final
treatment by removing harmful
bacteria, viruses, and nutrients.

The EPA Decentralized Wastewater Memorandum of Understanding (MOU) Partnership, created in
2005, has served as an ongoing cooperative relationship between the EPA and Signatory Organizations
to effectively and collaboratively address management and performance issues pertaining to

decentralized systems.


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WHERE IT'S WORKED

Shannock Woods Cluster Subdivison, Rl

Lamont, MS

This steep-sloped community, located in South Kingston, Rhode
Island, selected a 7,200 gallon per day cluster system for wastewater
treatment of a 16-lot cluster subdivision rather than installing multiple
individual systems. The decision aimed to minimize soil erosion,
maintain scenic views, and protect the drinking waters which is
located in a highly permeable aquifer recharge area. The selection
of a cluster system for the subdivision instead of individual onsite
systems drastically reduced the land needed for wastewater treatment
and disposal. It helped to preserve 50% of the land for open space
and to protect individual drinking water wells from contamination. The
system selected was able to remove 50% of the nitrogen.

Schematic of a cluster system

The community of Lamont, Mississippi, used decentralized
wastewater treatment including a septic tank effluent gravity
(STEG) collection system. This system was more affordable than
conventional treatment and better served the rural community
because of its simple operation and maintenance, iow energy
requirements and low operation and maintenance costs. This project
is 'green' because it uses energy wisely and allows the community to
reuse its wastewater in beneficial ways.

Ground breaking ceremony for Lamont Demonstration Project

ADDITIONAL RESOURCES

U.S. Environmental Protection Agency Office of Wastewater Management Decentralized Program-www.epa.gov/owm/onsite

Water Environment Research Foundation's Smart, Clean and Green: 21st Century Sustainable Water Infrastructure - http://www.werf.Org/i/c/
KnowledgeAreas/DecentralizedSystems/LatestNews/Smart_Clean_and_Gree.aspx

Decentralized Water Resource Collaborative's New Approaches in Decentralized Water Infrastructure - http://www.decentralizedwater.org/
documents/04-DEC-5SG/04DEC5Highlights.pdf

For more information on the individual MOU Partners, click on the logos below or go to http://www.epa.gov/owm/septic.

N#WRA

National Onsite Wastewater
Recycling Association

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ABSOCI^0

NAWT

GROUNDWATER

PROTECTION COUNCIL



Water Environment
Federation"

Preserving & Enhancing
the Global Water Environment

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National



Environmental

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Services



Center

NESC

Assistance. Solutions. Knowledge. \

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NATaT

National Association of Towns and Townships

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V— nW/SBBBBm for toxic substances O	Water Environment Research Foundation

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Collaboration. Innovation. Results.

Association of State Drinking
Water Administrators

Contact Information: tooke.maureen@epa.gov or 202-564-1162


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