Sewage or Septic Contamination in Buildings - Investigation, Testing and Remediation

How to inspect & test for sewage contamination and pathogenic or bacterial hazards in buildings
CLOGGED DRAIN DIAGNOSIS & REPAIR - separate article
SEWAGE BACKUP, WHAT TO DO - separate article with more advice for cleaning up after a sewage backup
SEWAGE & SEPTIC CONTAMINANTS - separate article
SEWAGE PATHOGENS in SEPTIC SLUDGE - separate article
Questions & Answers about testing for sewage contamination in buildings
References

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This article explains how to deal with and test for sewage backup contamination, sewage contamination testing, inspection, and cleanup- remediation in residential and commercial buildings. If you have had sewage back up and spill out of toilets into the building, cleanup is needed and you may face bacterial hazards. If you have had a sewage backup or burst house drain pipe in your building this document offers some advice on how to test for sewage contamination, bacterial and viral hazards, and links to sewage spill cleanup and bacterial hazard information regarding sewage and septic spill contamination. We explain why and how testing for sewage contamination is performed and we discuss the urgency of proper cleanup following a sewage backup or spill in a building.

The photo above shows what dirt and sewage sludge may look like in a basement after a sewer line backup. See BLOCKED DRAIN REPAIR METHODS to try clearing your blocked drain before going to more drastic measures.

Testing For Bacterial Contamination and Cleaning Up Sewage Backups in Buildings

If your building has had a septic or sewage system backup into the structure see SEWAGE BACKUP, WHAT TO DO and also see SEWAGE BACKUP PREVENTION. At SEWAGE BACKUP TEST & CLEANUP we discuss how to test for bacterial or other pathogens in a building - tests that may be useful after a sewage spill cleanup in order to assure that the building is acceptably clean.

At SEWAGE & SEPTIC CONTAMINANTS we list the pathogens and contaminants commonly found in sewage and in sewage backup waters. In this article series we explain the causes of sewer or septic backups into buildings, the health hazards, testing, and cleanup of sewage backups, and the cure or prevention of future sewage or septic backup problems.

Checking buildings for indoor air quality or other contaminants which may affect occupant health should not omit inspecting and taking site history for evidence of sewage or septic system backups into the structure or basement or crawl space areas below the structure. Gray water and black water (sewage) can cause a wide range of fungal, bacteriological, viral, and parasitic hazards in buildings.

The photo at left shows evidence of raw sewage overflow in the crawl space under a home. Although a new waste line was installed (the white pipe at the top of the photograph) no cleanup has been performed.

Both a one-time event and recurrent sewage leaks into a building would be a concern, particularly if prompt and competent cleaning were not performed. If recurrent sewage contamination has occurred more extensive building cleaning and treatment are likely to be required.

One reason that experts recommend very prompt treatment following a sewage backup in a building is the wish to avoid transmission of bacterial contamination to other building areas.

Examples of sewage bacteria and virus transmission might be by movement of people from contaminated areas to other building areas (tracking contaminated soil), and air movement of aerosolized particles or contaminated dust through the building by natural convection, heating and air conditioning equipment, or other sources of air and dust movement.

Testing for Sewage or Septic Contamination

PHOTO of sewage contamination effluent and water stains on the floor in a basement after a sewer line backup

The photograph shows a rather innocent-looking wet concrete basement floor following a sewer line backup into this building. In fact a very high level of pathogens was present on the concrete, on the lower portions of furnishings, and on and inside the paneled wall cavity.

Demolition, cleaning, and disinfection were needed. These surfaces were then re-tested after cleaning and disinfection were complete.

Additional testing was conducted to confirm that the workers did not contaminate other building areas during this cleanup.

While sewage may contain many pathogens harmful to building occupants, testing for this problem usually focuses on indicator organisms including total coliform, fecal coliform, Escherichia coli (E. coli), and Enterococcus as these species are expected in human sewage waste. They are potentially harmful themselves as well as serving as an indicator of sewage contamination.

Typical sampling methods to test for sewage contamination in buildings include use of sterile swabs on sample surfaces both in the suspected area and as a control in other building areas where low or no contamination is expected.

Bulk samples of debris or building materials may also be collected, such as drywall suspected of having been wet with a sewage backup. Samples are sent to a qualified laboratory for culture and examination for these bacteria.

Since there are a variety of tests for bacteria and for possible sewage contamination, specification of the definitive lab test for sewage contamination is important where health concerns are at stake. Be sure to review the test choices with your laboratory before ordering a specific test as test accuracy and cost vary widely.

Frequently Asked Questions (FAQs) About Sewage Spills in Buildings

Question: Hazards of & Best Response to a Sewage Spill in a Crawl Space

I am writing in the hope of getting some information on a sewage spill that happened at the place we are renting. We are in a studio unit that is below the original plumbing of the main building. There is a pump-up system to get rid of the sewage. It overflowed a couple of weeks ago because somebody previous to us had flushed tampons down the system and they had jammed the pump.

The effluent overflowed out of the top of the containment barrel and ran about 15'down the slope in the crawl space. At that time the landlord removed a good bit of the contaminated soil and then put kitty litter over it to absorb the moisture. Yesterday the tank overflowed again. This time, the plumber found a towel that had been flushed down the toilet, also by previous tenants. Our landlords had said they noticed the towel missing in mid August. It is now mid Nov. The plumber thought that it had just been floating in the collection barrel and was only a matter of time before it got sucked up by the pump.

This all happened in the crawl space below the unit we are renting. We are in Whistler BC and the house is built on the side of the mountain, so the crawl space is not the traditional type one visualizes when we think of a crawl space. Where the collection barrel is located, the space is just deep enough for the height of the barrel. By the entrance door of the crawl space, the ceiling to floor is well over 12'. Most of the are is mountain bedrock which is very jagged and sloping. As such, it is quite difficult to clean the area. This last spill has re-soaked the kitty litter from the previous spill.

My question to you is, are there health hazards due to the spill. My wife and I have somewhat compromised immune systems, so we have concerns about the consequences. The landlord had also stated that there was a continual problem with wet, damp soil in the crawl space. Would this lead to a mold problem. What would you suggest to clean up the spill, if anything. Would putting kitty litter or some other absorbing material be a good enough solution? Are there other steps that one could take to rectify the problem? Can the bacteria be transferred by walking in the affected area and then tracked into our living space? Or is it of no concern? I thank you for your time and I look forward to your response in the near future.- R.P. 10/14/2012

Reply: Advice for Disinfecting & Drying Out a Sewage Contaminated Crawl Space

We can't reliably assess the extent of health hazards in your home due to a crawl space sewage backup from just your note, as there are other very important considerations that an onsite expert would consider, such as the ease with which air or dust can move from a contaminated crawl area into the occupied building space. But here are some thoughts that may help:

An appropriate response to sewage spills in a crawl space goes beyond dumping some kitty litter on the ground. Missing from your description of how the sewage spill was handled in the crawl space you describe are these additional steps or considerations:

An inspection for mold or other contaminants in the same area, and further cleaning of surfaces as needed - see CRAWLSPACE MOLD ADVICE
Inspector for and removal/replacement (after surface cleaning) of any suspect or contaminated insulation or similar materials in the crawl area
Disinfection of the contaminated area. Professional cleaning companies use a variety of sanitizers and disinfectants beyond simple diluted bleach. The choice depends in part on just what surfaces and materials need treatment. Sanitizing a crawl space is described at CRAWL SPACE DRYOUT PROCEDURES
Measures to assure that sewage contaminated soil was not tracked into the living area, or appropriate cleaning there if needed. This may mean a few surface tests for sewage contaminants in the living area, starting with the most-suspect areas of floors.
Any possible effect on the building HVAC systems - for example a warm air heat or air conditioning duct system exposed to contamination.
Examination of the sewage ejector pump to remove any other pending blockages and to assure that the proper type of sewage grinder pump, check valves, piping, etc. are installed. See SEWAGE GRINDER PUMPS.
Installation of a warning system that indicates if the sewage pump is not working, so that residents can stop using toilets and fixtures long enough to fix the problem and avoid future sewage spills in the structure. Also see SEWAGE BACKUP PREVENTION and see Septic Pump Alarm Systems
In addition to removing contaminated soil (ok), typically we'd install a heavy plastic barrier to prevent soil moisture from continuing to enter the crawl area where it invites mold contamination. See CRAWL SPACE GROUND COVERS and CRAWL SPACE VAPOR BARRIER - also see CRAWL SPACE DRYOUT PROCEDURES to be sure there are not other sources of water entry into the crawl area.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

[1] "Remediation of Sewage Contaminated Crawlspaces", Byjim Holland, CR, "Cleaning and Restoration," July 1999, pp 22-24, original source: restcon.com/links/articles/Remediating%20Contaminated%20Crawlspaces.pdf
Escherichia coli O157:H7- US CDC
Demistifying Ecoli - Federation of Ontario Cottagers
Microbiology home page - US EPA
Cost effective testing for blackwater contamination in buildings Aerotech Labs
Indicator organisms, testing for sewage contamination in buildings Aerotech Labs
Sewage and Septic Contamination in Residential Buildings - consumer information and expert resources (this web page)
Sewage Pathogens in Septic Tank Sludge and Floating Scum: what makes up the contents of residential sewage
[9] Amahmid, O., Asmama, S., & Bouhoum, K. (1999). The effect of waste water reuse in irrigation on the contamination level of food crops by Giardia cysts and Ascaris eggs. International Journal of Food Microbiology, 49(1-2), 19-26.
[10] Barak, J.D., Whitehand, L.C., & Charkowski, A.O. (2002). Differences in attachment of Salmonella enterica serovars and Escherichia coli O157:H7 to alfalfa sprouts. Applied and Environmental Microbiology, 68(10), 4758-4763.
[11] Beuchat, L.R. (1996). Pathogenic microorganisms associated with fresh produce. Journal of Food Protection, 59(2), 204-216.
[12] Breuer, T., Benkel, D.H., Shapiro, R.L., Hall, W.N., Winnett, M.M., Linn, M.J., Timothy, J.N., Barrett, J., Dietrich, S., Downes, F.P., Toney, D.M., Pearson, J.L., Rolka, H., Slutsker. L., & Griffin, P.M. (2001). A multi-state outbreak of Escherichia coli O157:H7 infections linked to alfalfa sprouts grown from contaminated seeds. Emerging Infectious Diseases, 7(6), 977-982.
[13] Castro-Rosas, J., & Escartin, E.F. (2000). Survival and growth of Vibrio cholerae O1, Salmonella typhi, and Escherichia coli O157:H7 in alfalfa sprouts. Journal of Food Science, 65(1), 162-165.
[14] Charkowski, A.O., Barak, J.D., Sarreal, C.Z., & Mandrell, R.E. (2002). Growth and colonization patterns of Salmonella enterica and Escherichia coli O157:H7 on alfalfa sprouts and the effects of sprouting temperature, i inoculum /in·oc·u·lum/ (-ok´u-lum) pl. inoc´ula material used in inoculation.
[15] Evans, M.R., Ribeiro, C.D., & Salmon, R.L. (2003). Hazards of healthy living: Bottled water and salad vegetables as risk factors for Campylobacter infection. Emerging Infectious Disease, 9(10), 1219-1225.
[16] Frost, J.A., McEvoy, M.B., Bentley, C.A., Andersson, Y., & Rowe, B. (1995). An outbreak of Shigella sonnei infection associated with consumption of iceberg. Emerging Infectious Disease, 1(1), 26-28.
[17] Guo, X., Chen, J., Brackett, R.E., & Beuchat, L.R. (2001). Survival of Salmonellae on and in tomato plants from the time of inoculation at flowering and early stages of fruit development through fruit ripening, said of meat. See curing. . Applied and Environmental Microbiology, 67(10), 4760-4764.
[18] Guo, X., Chen, J., Brackett, R.E., & Beuchat, L.R. (2002). Survival of Salmonellae on tomatoes stored at high relative humidity, in soil, and on tomatoes in contact with soil. Journal of Food Protection, 65(2), 274-279.
[19] Guo, X., Iersel, M.W.V., Chen, J., Brackett, R.E., & Beuchat, L.R. (2002). Evidence of association of salmonellae with tomato plants grown hydroponically in inoculated nutrient solution. Applied and Environmental Microbiology, 68(7), 3639-3643.
[20] Itoh, Y., Sugita-Konishi, Y., Kasuga, E, Iwaki, M., Hara-Kudo, Y., Saito, N., Noguchi, Y, Konuma, H., & Kumagai, S. (1998) Enterohemorrhagic Escherichia coli enterohemorrhagic Escherichia coli EHEC Any of the E coli serotypes–eg O29, O39, O145 that produces shiga-like toxins, causing bloody inflammatory diarrhea, evoking a HUS. See Escherichia coli O157:H7, Hemolytic uremic syndrome. O157:H7 present in radish sprouts. Applied and Environmental Microbiology, 64(4), 1532-1535.
[21] Madden, J.M. (1992). Microbial pathogens in fresh produce--The regulatory perspective. Journal of Food Protection, 55, 821-823.
McMahon, M.A.S., & Wilson, I.G. (2001). The occurrence of enteric pathogens and Aeromonas species in organic vegetables. International Journal of Food Microbiology, 70(1-2),155-162.
[22] Puohiniemi, R., Heiskanen, T., & Siitonen, A. (1997). Molecular epidemiology of two international sprout-borne Salmonella outbreaks. Journal of Clinical Microbiology . 35(10), 2487-2491.
[23] Shearer, A.E., Strapp, C.M., & Joerger, R.D. (2001). Evaluation of polymerase chain reaction-based system for detection of Salmonella enteritidis, Escherichia coli O157:H7, Listeria spp., and Listeria monocytogenes on fresh fruit and vegetables. Journal of Food Protection, 64(6), 788-795.
[24] Takeuchi, K., Hassan, A.N., & Frank, J.F. (2001). Penetration of Escherichia coli O157:H7 into lettuce as influenced by modified atmosphere and temperature. Journal of Food Protection, 64(11), 1820-1823.
[25] Wright, C., Kominos, S.D., & Yee, R.B. (1976). Enterobacteriaceae and Pseudomonas aeruginosa recovered from vegetable salads. Applied and Environmental Microbiology, 31(3), 453-454.
[26] Thanks to reader Charles Labs at 247inktoner.com Tel: 800-866-8022 (a provider of ink toner, ink cartridges and related supplies) for updating our CDC link on e-Coli 4/19/2013.
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