USE OF SEWAGE EFFLUENT (RECLAIMED WATER) IN BATHROOM TOILETS
Never a good idea and still a very dangerous idea
Currently, the waste industry's public relation position is that it is perfectly safe to use pathogen contaminated
sewage effluent reclaimed water on school grounds, parks, lawns and in bath room toilets. As Gerba, et.al., noted in
a 1975 study, there is a dangerous risk involved. They stated, "The detection of bacteria and viruses falling out onto
surfaces in bathrooms after flushing indicated that they remain airborne long enough to settle on surfaces
throughout the bathroom. Thus, there is a possibility that a person may acquire an infection from an aerosol
produced by a toilet."
1: Appl Environ Microbiol. 2005 Jun;71(6):3163-70. Links
Validity of the indicator organism paradigm for pathogen reduction in reclaimed water and public health protection.
Harwood VJ, Levine AD, Scott TM, Chivukula V, Lukasik J, Farrah SR, Rose JB.
Department of Biology, SCA 110, University of South Florida, 4202 E. Fowler Ave., Tampa, Florida 33620, USA.
The validity of using indicator organisms (total and fecal coliforms, enterococci, Clostridium perfringens, and
F-specific coliphages) to predict the presence or absence of pathogens (infectious enteric viruses, Cryptosporidium,
and Giardia) was tested at six wastewater reclamation facilities. Multiple samplings conducted at each facility over a
1-year period. Larger sample volumes for indicators (0.2 to 0.4 liters) and pathogens (30 to 100 liters) resulted in
more sensitive detection limits than are typical of routine monitoring. Microorganisms were detected in disinfected
effluent samples at the following frequencies: total coliforms, 63%; fecal coliforms, 27%; enterococci, 27%; C.
perfringens, 61%; F-specific coliphages, approximately 40%; and enteric viruses, 31%. Cryptosporidium oocysts and
Giardia cysts were detected in 70% and 80%, respectively, of reclaimed water samples. Viable Cryptosporidium,
based on cell culture infectivity assays, was detected in 20% of the reclaimed water samples. No strong correlation
was found for any indicator-pathogen combination. When data for all indicators were tested using discriminant
analysis, the presence/absence patterns for Giardia cysts, Cryptosporidium oocysts, infectious Cryptosporidium, and
infectious enteric viruses were predicted for over 71% of disinfected effluents. The failure of measurements of single
indicator organism to correlate with pathogens suggests that public health is not adequately protected by simple
monitoring schemes based on detection of a single indicator, particularly at the detection limits routinely employed.
Monitoring a suite of indicator organisms in reclaimed effluent is more likely to be predictive of the presence of
certain pathogens, and a need for additional pathogen monitoring in reclaimed water in order to protect public health
is suggested by this study.
PMID: 15933017 [PubMed - indexed for MEDLINE]
1: Appl Microbiol. 1975 Aug;30(2):229-37. Links
Microbiological hazards of household toilets: droplet production and the fate of residual organisms.
Gerba CP, Wallis C, Melnick JL.
Large numbers of bacteria and viruses when seeded into household toilets were shown to remain in the bowl after
flushing, and even continual flushing could not remove a persistent fraction. This was found to be due to the
adsorption of the organsims to the porcelain surfaces of the bowl, with gradual elution occuring after each flush.
Droplets produced by flushing toilets were found to harbor both bacteria and viruses which had been seeded. The
detection of bacteria and viruses falling out onto surfaces in bathrooms after flushing indicated that they remain
airborne long enough to settle on surfaces throughout the bathroom. Thus, there is a possibility that a person may
acquire an infection from an aerosol produced by a toilet.
PMID: 169732 [PubMed - indexed for MEDLINE]
J Appl Microbiol. 2005;99(2):339-47. Links
The potential spread of infection caused by aerosol contamination of surfaces after flushing a domestic toilet.
Barker J, Jones MV.
Department of Pharmaceutical and Biological Sciences, School of Life and Health Sciences, Aston University, Aston
Triangle, Birmingham, UK. firstname.lastname@example.org
AIMS: To determine the level of aerosol formation and fallout within a toilet cubicle after flushing a toilet
contaminated with indicator organisms at levels required to mimic pathogen shedding during infectious diarrhoea.
METHODS AND RESULTS: A semisolid agar carrier containing either Serratia marcesens or MS2 bacteriophage was
used to contaminate the sidewalls and bowl water of a domestic toilet to mimic the effects of soiling after an episode
of acute diarrhoea. Viable counts were used to compare the numbers of Serratia adhering to the porcelain surfaces
and those present in the bowl water before and after flushing the toilet. Air sampling and settle plates were used to
determine the presence of bacteria or virus-laden aerosols within the toilet cubicle. After seeding there was a high
level of contamination on the porcelain surfaces both under the rim and on the sides of the bowl. After a single flush
there was a reduction of 2.0-3.0 log cycles cm(-2) for surface attached organisms. The number of micro-organisms
in the bowl water was reduced by 2.0-3.0 log cycles ml(-1) after the first flush and following a second flush, a further
reduction of c. 2.0 log cycles ml(-1) was achieved. Micro-organisms in the air were at the highest level immediately
after the first flush (mean values, 1370 CFU m(-3) for Serratia and 2420 PFU m(-3) for MS2 page). Sequential
flushing resulted in further distribution of micro-organisms into the air although the numbers declined after each
flush. Serratia adhering to the sidewalls, as well as free-floating organisms in the toilet water, were responsible for
the formation of bacterial aerosols. CONCLUSIONS: Although a single flush reduced the level of micro-organisms in
the toilet bowl water when contaminated at concentrations reflecting pathogen shedding, large numbers of
micro-organisms persisted on the toilet bowl surface and in the bowl water which were disseminated into the air by
further flushes. SIGNIFICANCE AND IMPACT OF THE STUDY: Many individuals may be unaware of the risk of
air-borne dissemination of microbes when flushing the toilet and the consequent surface contamination that may
spread infection within the household, via direct surface-to-hand-to mouth contact. Some enteric viruses could
persist in the air after toilet flushing and infection may be acquired after inhalation and swallowing.
PMID: 16033465 [PubMed - indexed for MEDLINE]
1: J Appl Microbiol. 2000 Jul;89(1):137-44. Links
Survival of Salmonella in bathrooms and toilets in domestic homes following salmonellosis.
Barker J, Bloomfield SF.
Pharmaceutical Sciences Institute, School of Life and Health Sciences, Aston University, Birmingham, UK.
The survival and environmental spread of Salmonella bacteria from domestic toilets was examined in homes, where
a family member had recently suffered an attack of salmonellosis. In four out of six households tested, Salmonella
bacteria persisted in the biofilm material found under the recess of the toilet bowl rim which was difficult to remove
with household toilet cleaners. In two homes Salmonella bacteria became incorporated into the scaly biofilm adhering
to the toilet bowl surface below the water line. Salmonella enteritidis persisted in one toilet for 4 weeks after the
diarrhoea had stopped, despite the use of cleaning fluids. Salmonellas were not isolated from normally dry areas
such as, the toilet seat, the flush handle and door handle. Toilet seeding experiments were set up with Salmonella
enteritidis PT4 to mimic environmental conditions associated with acute diarrhoea. Flushing the toilet resulted in
contamination of the toilet seat and the toilet seat lid. In one out of three seedings, Salmonella bacteria were also
isolated from an air sample taken immediately after flushing, indicating that airborne spread of the organism could
contaminate surfaces in the bathroom. In the seeded toilet Salmonella bacteria were isolated from the biofilm in the
toilet bowl below the waterline for up to 50 d after seeding, and also on one occasion from the bowl water. The
results suggest that during diarrhoeal illness, there is considerable risk of spread of Salmonella infection to other
family members via the environment, including contaminated hands and surfaces in the toilet area.
PMID: 10945790 [PubMed - indexed for MEDLINE]
1: Water Sci Technol. 2002;46(6-7):311-6. Links
Microbiological investigations of rainwater and graywater collected for toilet flushing.
Environment & Resources DTU, Technical University of Denmark, Lyngby.
Seven Danish rainwater systems were investigated with respect to the microbial water quality. The general
microbiological quality (total numbers of bacteria (AODC)), and heterotrophic plate counts on R2A and Plate Count
Agar in the toilets supplied with rainwater were approximately the same as in the reference toilets supplied with
drinking water. However, in 12 of the 27 analysed samples one or more pathogens were observed (Aeromonas sp.,
Pseudomonas aeruginosa, Legionella non-pneumophila, Campylobacter jejuni, Mycobacterium avium, and
Cryptosporidium sp.). These pathogens were not found in any of the reference toilets (32 toilets). This means that
the use of rainwater introduced new, potentially pathogenic microorganisms into the households which would
normally not occur in toilets supplied with water from waterworks. Furthermore, four graywater systems were
investigated where water from the shower and hand wash basin was reused. The graywater systems gave more
problems in terms of bad smell and substantially higher numbers of E. coli and Enterococcus in some toilet bowls
supplied with graywater.
PMID: 12381006 [PubMed - indexed for MEDLINE]
1: Epidemiol Infect. 2007 Jul;135(5):818-26. Epub 2006 Nov 17. Links
Gastroenteritis associated with accidental contamination of drinking water with partially treated water.
Fernandes TM, Schout C, De Roda Husman AM, Eilander A, Vennema H, van Duynhoven YT.
European Programme for Intervention Epidemiology Traning, National Institute for Public Health and the
Environement (RIVM), The Netherlands.
Due to human error, drinking water supplied to a new housing estate in The Netherlands was contaminated with grey
water. The cohort of 921 accidentally exposed households (area A) had a higher attack rate for diarrhoea (54.1%)
than a non-exposed cohort of 1529 households from an adjacent area (B) (24%) (RR 2.3, 95% CI 1.9-2.7).
Household water score showed a dose-response with illness, in both areas A and B. For each 1000 inhabitants, 19.8
cases in area A, 7.0 cases in control area B (RRAB 2.2, 95% CI 1.3-3.8) and 3.3 cases in a more distant control
area C (RRAC 4.6, 95% CI 2.7-8.0) were diagnosed with gastroenteritis by their general practitioner. A
gastroenteritis outbreak associated with consumption of contaminated drinking water was observed in the exposed
area. The use of grey water was banned in 2003, with the exception of rainwater use for flushing toilets. The risk of
rainwater use is currently being investigated.
PMID: 17109770 [PubMed - indexed for MEDLINE]
1: Water Sci Technol. 2004;50(2):165-72. Links
Microbiological water quality in a large in-building, water recycling facility.
Birks R, Colbourne J, Hills S, Hobson R.
Thames Water Innovation and Development, Manor Farm Road, Reading, RG2 0JN, UK.
The Thames Water recycling plant at the Millennium Dome, London, reclaimed three sources of water: greywater
from the washbasins, rainwater from the Dome roof and groundwater from a borehole on site. These were
pre-treated separately, and the mixed stream filtered using ultrafiltration and reverse osmosis membranes.
Monitoring for indicator microorganisms was undertaken throughout the plant and in the reclaimed water distribution
system, as well as ad-hoc monitoring for the presence of pathogens in the raw waters. Treatment to the level of
ultrafiltration was more than adequate to produce a water quality meeting existing worldwide reclaimed water
guidelines for toilet flushing. Owing to the excellent quality of the water leaving the plant, no significant
microbiological growth was observed in the reclaimed water distribution system during the year. The raw greywater
exhibited a higher faecal bacterial load than the rainwater and groundwater, as predicted from more human contact
(i.e. hand washing). Environmental strains of Legionella were observed in the three raw greywater samples analysed
for pathogens, as was Cryptosporidium, Giardia and faecal enterococci. The rainwater had relatively high levels of
faecal bacteria, probably of avian origin. Giardia was detected in one rainwater sample confirming the potential for
this water source to contain pathogens.
PMID: 15344787 [PubMed - indexed for MEDLINE]