The Effectiveness of Vault-Toilet Odor-Control Products: An Update

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

treated toilets.

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

recreation sites.

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 Update

Mark Zavala, Mechanical Engineer

Brenda Land, Senior Sanitary Engineer



United States Department of Agriculture

Forest Service


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

recreation sites.


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 per gallon.

No Stink Special Powder One quart. Once or twice a $75 per 5-gallon

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.


Field Results

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

treatment stops.

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

SDTDC’s national publications are available on the

Internet at:

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:


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): • Internet e-mail:


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 be suitable.

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