For additional information, contact:
Recreation Management Program
Leader, San Dimas Technology & Development Center,
444 East Bonita Avenue, San Dimas, CA 91773-3198; Phone
909-599-1267; TDD; 909-599-2357; FAX: 909-592-2309
Lotus Notes: Mailroom WO SDTDC@FSNOTES • Intranet (web
site): http://fsweb.sdtdc.wo.fs.fed.us • Internet e-mail: firstname.lastname@example.org
From campground hosts to recreation technicians,
many people need to manage vault-toilet odor to
minimize its adverse impact on recreational visitors
to Forest Service, U.S. Department of Agriculture,
lands. There are many products marketed as
vault-toilet additives to eliminate odor. The purpose
of this study was to find effective products. One
product, Armor Research’s “Blanket 510” (figure 1),
did significantly reduce odors in both the laboratory
study and in field tests. The product had the added
benefit of reducing fly populations around the
Figure 1—Armor Research’s “Blanket 510.”
In 1990, San Dimas Technology and Development
Center (SDTDC) conducted an evaluation on
a variety of biological and chemical products
claiming to control unpleasant odors emanating
from vault-toilet waste. The 8-week study
concluded that none of the products tested was
satisfactory as a vault toilet additive (Hoshide).
Many new and revised odor-control products
have come on the market since 1990 (figure 2),
and vault-toilet odor is still a problem at some
Figure 2—New odor-control products.
A 6-week laboratory study in 2004 found similar
results to the 1990 study for most products.
However, three products seemed to warrant further
evaluation. BioWorld’s “Liquid Optimizer Plus,”
NoStink’s “Special Powder,” and Armor Research’s
“Blanket 510” did reduce odors during the study
and were field-tested during the summer of 2006.
The Effectiveness of Vault-Toilet Odor-Control Products: An
Mark Zavala, Mechanical Engineer
Brenda Land, Senior Sanitary Engineer
DEPARTMENT OF AGRICULTURE
United States Department of Agriculture
Vault toilets differ from flush toilets—with sewage
or septic systems—because they are waterless
and the solid and liquid waste accumulates inside
a sealed vault (typically 500- to 1,500-gallon
capacity) until it is pumped out. Vault-toilet odors
are primarily attributed to ammonia and gases
from the anaerobic decomposition of the organic
(fecal) matter present. Odors also can be caused
by other substances (such as trash, food, drinks,
etc.) dumped in the vault. The importance of odors
in low concentrations is an aesthetic issue as
opposed to a health issue.
The focus of this study was to determine the
validity of odor-elimination claims made by
manufacturers of odor-control products in their
application to the waterless vault-toilet system.
The study was not intended to be a complete
scientific analysis, but rather to establish a
practical guide for those odor-minimizing products
suitable for Forest Service vault-toilet use at
The majority of the products studied are best
suited for septic systems, sewage treatment
plants, and other systems that receive influent
water, according to their marketing and directions
for use. The waterless vault-toilet system, which
receives only pure waste as influent, is very
concentrated and can have biochemical oxygen
demand 50-times higher than a septic or sewer
system (Hoshide). The high biochemical oxygen
demand and high solids content may have an
adverse effect on the products’ function.
Some products studied increased foul odors, when
compared with the control samples. The control
samples were allowed to undergo natural bacterial
processes, resulting in greatly diminished odor
over the 6-week study period.
The following products seemed to work during the
laboratory study, and were further studied under
actual vault-toilet conditions (table 1). A product
cost comparison is shown in table 2.
Manufacturer Product Form Type
BioWorld Liquid Optimizer Plus Liquid Biological
No Stink Special Powder Granular Mineral
Armor Research Blanket 510 Liquid Solvent based
Table 1—Products field tested.
Manufacturer Product Treatment Frequency Cost (2006)
BioWorld Liquid Optimizer Plus One quart. Once a week. $63
No Stink Special Powder One quart. Once or twice a $75 per
week, as needed. bucket.
Armor Research Blanket 510 Enough to make a Once when vault
$10.59 per gallon
1⁄4-inch-thick blanket is pumped. 5 to 10 gallons
(6.5 square feet per needed.
Table 2—Cost comparison summary.
BioWorld’s Liquid Optimizer Plus
Liquid Optimizer Plus is applied with a wand
and pressure sprayer to mist the vault walls and
surface of the vault content. It reduces odor and
almost eliminates flies when added to the vault
weekly. Odor and flies return to pretreatment levels
when treatment stops.
No Stink’s Special Powder
Special Powder is a granular product broadcast
across the surface of the vault’s content. It
minimizes odor for 2 or 3 days after treatment.
Odor and flies return to pretreatment levels when
Armor Research’s Blanket 510
Blanket 510 is poured through the manhole or vault
riser after the vault is pumped and surcharged with
water. The product is lighter than water and floats
on the surface (see figure 3). It can be sprayed
onto the vault walls for additional odor reduction.
It minimizes both odors and flies and is added
only when the vault is pumped and recharged with
Figure 3—Blanket 510 floats on top of liquid.
Hoshide, G. T. 1991. Do biological or chemical
additives really control vault toilet odors? GTR-
9123-1203-SDTDC. San Dimas, CA: Forest
Service, U.S. Department of Agriculture, San
Dimas Technology and Development Center.
SDTDC staff thanks Kathie Snodgrass, architect,
Missoula Technology and Development Center and
Ellen Eubanks, landscape architect, SDTDC for
their review of this publication.
SDTDC staff also thanks Jeff Bloom, special
uses and recreation, Umatilla National Forest,
Walla Walla Ranger District (R6); Jason R. West,
developed recreation, Medicine Bow-Routt
National Forest, Yampa District (R2); Chris A. Hill,
Apache-Sitgreave National Forest, Alpine Ranger
District (R3); John Ladley, recreation officer, San
Bernardino National Forest, San Jacinto Ranger
District (R5); and Bill Mertens, engineering
technician, Kisatchie National Forest (R8) for
volunteering to field test the three products.
For further information on odor control in vault
toilets contact Brenda Land by phone at 909–599–
1267 ext. 219; or by e-mail at email@example.com.
SDTDC’s national publications are available on the
Forest Service and U.S. Department of the Interior
Bureau of Land Management employees also can
view videos, CDs, and SDTDC’s individual project
pages on their internal computer network at:
The information contained in this publication has been
developed for the guidance of employees
of the Forest Service, U.S. Department of Agriculture, its
contractors, and cooperating
Federal and State agencies. The Forest Service assumes no
responsibility for the interpretation
or use of this information by other than its own employees.
The use of trade, firm, or
corporation names is for the information and convenience of
the reader. Such use does not
constitute an official evaluation, conclusion,
recommendation, endorsement, or approval of
any product or service to the exclusion of others that may
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