United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-86/069 Sept. 1986
<&EPA Project Summary
Field Investigation of
Biological Toilet Systems and
Grey Water Treatment
K. M. Enferadi, R. C. Cooper, S. C. Goranson, A. W. Olivieri,
J. H. Poorbaugh, M. Walker, and B. A. Wilson
Operational characteristics and over-
all acceptability were determined for
popular models of biological toilets and
a few select grey water systems. A field
observation scheme was devised to
take advantage of in-use sites through-
out the State of California. Field
performance was recorded monthly on
forms developed to record site condi-
tions such as pile temperatures, odors,
and vector observations. Samples of
the decomposition chamber pile and
the end products were taken for labora-
tory analyses that included both physi-
cal and microbiological parameters.
Grey water influent and effluent were
also analyzed.
A health risk assessment was per-
formed concurrently using environ-
mental health experts to estimate the
probability of a significant failure for a
particular onsite waste treatment and
disposal system. The health experts
used an objective decision-making
technique that may be used by regula-
tory officials to evaluate new technolo-
gies where there is an absence of defini-
tive test information. This assessment
results in a probability that is expressed
in relation to the estimated risk of a
known system, the septic tank/soil ab-
sorption system.
Model frameworks for education and
surveillance monitoring are presented.
Since the user may need guidance dur-
ing siting and operation and in the
event of system failures, third-party
management is strongly advised.
This Project Summary was devel-
oped by EPA's Water Engineering Re-
search Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
This study was undertaken to assess
performance characteristics, operation
and maintenance problems, and health
risks for seven types of non-water-
carriage toilets and associated grey
water treatment systems. The biological
toilet systems assessed through field
studies included home-built and com-
mercially available designs. Grey water
treatment systems were generally vari-
able in design and were essentially
those associated with the biological toi-
let systems chosen for study.
The health risk assessment technique
used in the study relied on the judgment
of two tiers of experts in the field of pub-
lic health to assess the relative risk of an
unknown system compared with a
known system performing under simi-
lar conditions.
The study was initiated to address the
potential public health problems posed
by the increasing popularity of biologi-
cal toilets and grey water treatment and
disposal systems among ecologically
concerned individuals in California and
elsewhere in the United States.
Experimental Procedures
The site selection process began in
February 1978 when all local directors
of environmental health in California's
58 counties were contacted and invited
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to participate. Systems were selected in
10 counties, and monitoring was com-
pleted in the following 8: Calaveras,
Humboldt, Kern, Marin, Mendocino,
Monterey, Nevada, and Sonoma. An ef-
fort was made to obtain representative
systems in as many varying environ-
mental and physical situations as possi-
ble, but all sites and units were to meet
the following criteria:
1. Units were officially recognized
and in compliance with existing
local requirements of county
health departments and/or local
regulatory bodies.
2. Units were slated for year-round
use.
3. Occupants were willing to allow a
year of unit monitoring.
4. County health officials and site
owners agreed on the liability and
confidentiality of the study.
The units selected under these criteria
were subject to monthly visits by the
field staff, who were either county
health sanitarians or project staff from
the Department of Health Services
(DOHS). As the study progressed, the
number of units monitored monthly
varied. This variation resulted from site
inaccessibility (especially during winter
months), withdrawal of site owners
from the study, absence of occupants
on the day of inspection, inconsistent or
seasonal use of units by the occupants,
discontinuation of unit use during
change of occupants, or failure of the
field investigator to perform.
The most rigorous sampling took
place between August 1979 and June
1980, when laboratory services were
available to the project. Six units in
Marin County were added in August
1979, and another three units in Cala-
veras County were added in November
1979. The type of laboratory work
ordered for each site was predeter-
mined in an effort to develop informa-
tion about all system types. Analytical
results were generally not available to
project staff for 3 to 5 months after sam-
pling and thus did not influence choices
until the last few months, when an effort
was made to follow up earlier findings.
Table 1 summarizes the types and num-
ber of systems examined during the
data collection phase.
The objective of the field sampling
and monitoring work was to obtain as
much information as possible on the
operation and performance of the se-
lected systems and on the biological,
physical, and chemical aspects of the
stored excreta solids, liquid, and grey
Table 1. Systems Examined from February 1979 through June 1980
Type of Toilet No. Examined
Waterless Toilets:
Large, sloped fiberglass toilets
Large, sloped plastic toilets
Box-like humus toilet with topping bar
Box-like humus toilet with rotor
Vault privy
Pit privy
Drum toilet
Total
Grey Water Systems:
Septic tank
Proprietary settling tank
Single medium filter
Dual media filter
No treatment
Total
32
7
2
1
2
3
water collection and treatment over a
12-month period (i.e., systems' per-
formance over the four seasons). No at-
tempt was made to control the amount
of usage of the units by the occupants
or to influence the users' decisions
about operating and maintenance prac-
tices.
All persons involved in the routine
sampling and monitoring were individ-
ually instructed on their first site visit by
the field biologist and/or the project di-
rector to standardize the data collection
activities as much as possible. To facili-
tate accurate and uniform recording of
observations and data at each site visit,
personnel were provided with written
instructions and a field survey form de-
signed by project staff.
Data and Sample Collection
from Waterless Toilets
Observation of Site and Unit
Conditions
Upon arriving at the site, the field in-
vestigators noted wind direction and
speed. Moving upwind toward the unit,
they recorded any odor associated with
the toilets at distances of 100 and 50 ft
from the toilet vent stack and at the res-
idence. Distinction was made between
hydrogen sulfide and ammonia odors.
The investigators then interviewed the
occupants concerning general and
specific details of the unit operation,
problems, and extent of use. Entering
the bathroom or privy house, they
noted the presence of any odor at the
toilet port and looked for signs of exces-
sive numbers of flies or other insects in
the room.
At the vault of the unit, investigators
recorded signs of spillage, leakage, vec-
tor invasion, and odors. The access port
was opened, and the inside of the vault
was examined by flashlight for
arthropods. Odors within the vault were
noted along with distribution of accu-
mulated solids and liquids, leaks, struc-
tural problems, etc.
Temperatures were taken at the cen-
ter and at the edge of the solids pile,
each at one-half the depth of the pile. In
units with separation of fresh and de-
composed solids, temperatures were
taken in each pile. For units with heating
coils, an additional reading was made
near the coil.
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To determine solids pH in the field,
investigators used non-bleeding Color-
pHast* indicator strips with pH ranges
of 4.0 to 7.0 and 6.5 to 10.0. The status of
solids decomposition was described
based on particle size and uniformity,
color, and distribution of moisture.
Before closing the vault, investigators
took samples of solids for submission to
the Berkeley laboratories of the DOHS,
and they replaced the exposed sticky fly
tapes and cockroach traps with new
ones.
Observations and Sampling
of Arthropods
During each site visit, investigators
collected representative specimens of
insects, spiders, mites, and other
arthropods associated with the units.
Flying insects were taken with an insect
net. Arthropods crawling on the solids
and vault walls were picked up with for-
ceps or a camel's hair artist's brush
moistened with alcohol. The presence
of mites or other arthropods on or in the
immediate area of the toilet seat or
kitchen port (if installed) was deter-
mined by swabbing these ports with a
white cotton flannel mitten.
The occurrence of flying insects dur-
ing the previous month was determined
by hanging sticky fly tape in the vault at
a location out of the way of fouling. To
detect the presence of cockroaches, a
cockroach sticky trap was placed in a
corner of the vault.
Samples of solids for arthropod ex-
traction were taken from both the
fresher pile in the vault and from the
decomposed pile in the removal cham-
ber if present. Each of these samples
was a composite of four subsamples
taken at the edge, center, and intermedi-
ate levels in the pile; the total sample
amounted to approximately 1L.
Sample Collection for Basic
Laboratory and Pathogen
Analyses
Samples of solids for the various mi-
crobiological, physical, and chemical
analyses were also taken from the
vaults with a plastic-bag-lined scoop.
The areas from which samples were
selected in the solids mass of fresh ma-
terial, intermediate-aged material, and
finished (decomposed) material varied
with the specific analysis needs of the
unit being sampled.
"'Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use.
Leachate accumulation in the vaults
was sampled by suction using a plastic
turkey baster. Samples for microbiolog-
ical tests were submitted in sterile 4-oz
plastic bottles containing sodium thio-
sulfate as a dechlorinating agent. Sam-
ples for physical and chemical analyses
were put into a clean 1/2-gal plastic bot-
tle.
Data and Sample Collection
from Grey Water Systems
At sites of grey water systems, inves-
tigators were to examine the immediate
area for signs of leakage and overflow
resulting from surge loading of the
treatment unit. The presence and ab-
sence of odors and insects, especially
mosquitoes, were noted. Upon opening
the access port, investigators were to
observe and report degrees of scum
layer and settled solids buildup. Dis-
posal areas were not routinely sub-
jected to observation. Water samples
were removed from the treatment unit
using the same methods described for
leachates. In the systems where grey
water was treated, grab samples of both
the influent and the effluent were taken.
Sample Storage and Transport
All field-collected samples were
shipped to the DOHS laboratories in
Berkeley in 32- x 20- x 14-in. insulated
boxes. The samples rested on four blue
ice packs held in place with covers of
4-in.-thick flexible foam cut to fit the
boxes Most shipments were made by
Greyhound Bus within the 30-hr period
specified by the laboratories for uni-
form microbiological analyses. Upon
arrival at the Berkeley facility, any sam-
ples to be composited for the basic lab-
oratory and pathogen analyses were
well mixed under a hood, and aliquots
were transferred to separate containers
for the bacterial, viral, and parasite
screens, as required. Temperatures of
the sample were not taken upon arrival
at the laboratory, but with few excep-
tions, the blue ice packs were still par-
tially frozen, and the samples were thor-
oughly cooled.
Specific analytical methods for vector
extraction, identification of arthropods,
coliform assays, bacteria and parasite
screens, parasite confirmation and vi-
ability determination, and virus assays
are detailed in the full report. Physical
and chemical analyses were performed
according to U.S. Environmental Pro-
tection Agency and Standard Methods.
Risk Assessment Procedure
Risk assessment was performed by
the probability matrix technique (PMT),
which required two groups of health ex-
perts. The first group delineated health
problems that might be associated with
a given process and estimated the prob-
ability of their occurrence. The second
group judged the severity of the prob-
lems delineated by the first group.
Members of the first group included
bacteriologists, virologists, parasitolo-
gists, entomologists, sanitary engi-
neers, and similar professionals. They
were instructed to make judgments on
the probability of problem occurrence
and to place a value on the probability
using a linear scale of zero to one. In
such a scale, values of less than 0.5 indi-
cate that the problem is not likely to
occur.
Members of the second group were
all physicians who were directed to
make judgments concerning the sever-
ity of the problems named by the first
group. Relative severity was ranked
from 0 to 100, with 100 being the most
severe and 0 the least. Relative judg-
ments about the severity of a problem
were made in relation to the other prob-
lems being considered and not to some
absolute level of severity. The severity
judgments were medical opinions
based on collective knowledge of the
life expectancy, degree of disability, and
treatment effectiveness associated with
the public health problems considered.
Results and Conclusions
Evidence suggested that performance
of the biological toilets varied from
mere storage of human excrement to
partially successful decomposition of
organics and/or reduction of microbio-
logical hazards. The physical presence
of solids at the final chamber of a toilet
system had no bearing on whether or
not treatment had occurred. The rate at
which excrement moved through a sys-
tem depended solely on system capac-
ity and rate of usage. In addition, the
physical appearance and odor charac-
teristics were not reliable indicators of
the biological degradation process.
Most of the system users were advo-
cates of alternative technology, yet they
were generally unable to make their
systems work satisfactorily. Few of
these systems displayed any significant
evidence of biological composting dur-
ing 17 months of observation. The sys-
tems repeatedly showed evidence of
conditions unfavorable for the occur-
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rence of biological composting—for ex-
ample, inadequate use of bulking agent,
too much moisture, anaerobic condi-
tions, insect vectors, and ambient tem-
peratures. The users were generally not
well informed about the particular sen-
sitivities of their systems to improper
operating procedures. Since a majority
of the users were unwilling and/or un-
able to perform recommended opera-
tion and maintenance procedures, it is
unclear whether any of the toilet sys-
tems studied were capable of accept-
able performance.
Problem Areas Identified
The following are apparent problem
areas identified with the proprietary toi-
let units studied:
1. Small or awkwardly placed open-
ings limited physical access to the
stored excrement and either pre-
vented or hindered the users from
performing routine maintenance.
2. Existing internal structural design
features or mechanisms intended
to mix and/or aerate solids (e.g.,
slanted chamber bottom or inter-
nal rotors) failed to do so.
3. Some of the proprietary devices
suffered structural failures such as
topping bar handle breakage
under normal use, air baffle col-
lapse under the weight of the ex-
crement pile, metal fastener corro-
sion, inefficient latches, leaking
holding chamber design, and
other construction defects.
4. Electrical components such as
heating elements malfunctioned
and/or did not perform as in-
tended.
5. Venting systems used in the stud-
ied units could not maintain aero-
bic conditions within the excre-
ment pile, nor could they mitigate
excessive moisture.
6. Stored excrement attracted and
harbored insects even though the
units were reportedly designed to
prevent this problem.
7. The manufacturer's instructions to
the user were not always available
in English. When instructions were
available, they uniformly lacked in-
formation necessary to under-
stand the degradation process and
often contained unsubstantiated
and misleading information about
the quality and safety of the end
products.
Problem areas identified with
homeowner-built toilet units are as fol-
lows:
1. Poor siting allowed the excrement
chamber to become inundated
with surface and/or storm runoff.
Some subsurface excrement
chambers were flooded by a rising
groundwater table during wet
weather.
2. Inadequate or missing seals and/or
screens over all openings allowed
insect and rodent vector access to
the excrement pile.
3. Cumbersome access doors hin-
dered vault owners during opera-
tion and maintenance, and the lack
of access to drum contents pre-
vented user maintenance activity.
4. Uncoated drums frequently cor-
roded.
5. When the recommended scissor-
jack arrangement was not used to
position the drum, full drums were
difficult to remove for ultimate dis-
posal.
Most of the grey water treatment sys-
tems studied also failed to perform their
functions successfully. Analytical work
performed during this investigation
demonstrated that individual house-
holds produced highly variable grey
water of a quality similar to raw domes-
tic sewage. Merely separating toilet
wastes frorr the remainder of the
household waste stream does not in-
sure persona! or public safety. Both
clothes washing and bathing activities
produced a wide range of indicator or-
ganisms. The major portion of coli-
forms detected were of fecal origin.
None of the treatment and/or segrega-
tion schemes resulted in a reduction of
microbiological hazards or a discernible
wastewater treatment. Only one treat-
ment scheme (involving a series of set-
tling tanks) resulted in consistent re-
moval of particulate matter.
Nearly all reuse schemes involved
seasonal irrigation of landscape and/or
food crops, but most were used year-
round and had no provisions for ulti-
mate disposal of poor-quality grey
water and surge loads or for storage
when use was contraindicated by wet
weather. Homeowners did not establish
a routine program for operating and
maintaining their systems. They were
generally aware of them only when mal-
functions or problems occurred, and
even then they did not place a high pri-
ority on resolving the matter.
Health Risks
The judgments made by environmen-
tal health experts indicate that the risk
of a public health problem occurring in
a septic tank/soil absorption system
during the lifetime of the system is 1
chance in 500,000. The public health risk
associated with the various combined
black and grey water disposal systems
ranged from 1 chance in 30,000 (for true
composting, mouldering, and buried
drum toilet waste with landscape-
disposed grey water) to 1 in 2,300 (for
drum toilet waste and grey water dis-
posed on food crops). Systems were as-
signed smaller health risks when they
did not involve food crops. For example,
the risk associated with true compost-
ing systems in which solids are buried
and grey water is used for landscape
irrigation was 1 in 30,000, whereas the
risk was 1 in 7,000 when grey water was
applied to food crops (a fourfold in-
crease of risk). Numerical values are rel-
ative only, but they are useful for com-
paring different systems.
System maintenance potentially in-
creased the health risk to individual
users/but differences in the level of sys-
tem maintenance would have a limited
effect on risk to the community's health,
depending on population and system
density.
The full report was submitted in fulfill-
ment of Grant No. R805942 by the Cali-
fornia Department of Health Services
under the partial sponsorship of the
U.S. Environmental Protection Agency.
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K. M. Enferadi, R. C. Cooper, S. C. Goranson, A. W. Olivieri, J. H. Poorbaugh, M.
Walker, and B. A. Wilson are with State of California, Department of Health
Services, Berkeley, CA 94704.
Steven W. Hathaway and James F. Kreissl are the EPA Project Officers (see
below).
The complete report, entitled "Field Investigation of Biological Toilet Systems and
Grey Water Treatment,"(OrderNo. PB86-234 648'/AS; Cost: $22.95, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officers can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-86/069
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