Portable Toilets and the Germs they Attract

Portable Toilets and the Germs they Attract from Aim Hire

By: Aim Hire  21-Sep-2011
Keywords: Toilets, Portable Toilets


Portable toilets and the germs they attract!

By Elise Kelsey, Marketing Manager, Aim Hire.

Have you ever cringed at the thought of using your portable site toilet? Imagine the germs!

As it turns out, your accountant probably has more germs festering on his office desk than are present and ready to infect on the toilet seat! Hard to believe isn’t it, but according to studies by world renowned germ expert, Dr Charles Gerber PhD from the University of Arizona, an office desk with its keyboard full of lunch crumbs and grimy phone handset,  is likely to be 50 times germier  than a toilet seat (Accountants rated just below school teachers when it came to the most highly bacteria laden work desks)!

Gerber, a US microbiologist, became famous after publishing his 1975 paper “Microbiological Hazards of Household Toilets”.* Since then he has written over 400 peer reviewed journal articles and  commented on environmental germs and where they might be found in the highest concentrations. Gerber is regularly interviewed and quoted throughout the world and is quick with his anecdotes when relating his findings to the real world. According to Gerber, the kitchen sponge and sink have a significantly higher germ count than the household toilet seat. Bacteria from raw meat and food products tend to thrive in moist environments, whereas the toilet seat itself is too dry to support a colony of bacterial nasties. To quote Gerber, “If an alien came from space and studied the bacterial counts, he probably would conclude he should wash his hands in your toilet, and sh@% in your sink.”!

But how do these findings relate directly to portable site toilets? To find out, Aim Hire commissioned an independent study prepared by Dr Derio Comar, Microbiolgist at Sharpe and Howells Pty Ltd, chartered chemists.* The study was commissioned to assess the hygiene status of portable toilets under normal operational conditions.

The study by Sharpe and Howell looked at whether the frequency of emptying  sewage tanks has an influence on the microbiology of the toilet and how the status of current cleaning techniques (or services) affects the state of the toilet.

The study commenced at the beginning of March 2011 and operated for a period of two weeks across more than 50 building sites in the northern suburbs of Melbourne. All the toilets included in the study were already commissioned at the construction sites and represented normal Aim Hire contracts and standard servicing agreements. The sites chosen for the study were all single  dwelling construction sites with one portable hire toilet on site.

To assess the standard of hygiene of the portable toilets, Sharpe and Howell conducted microbiological tests of the toilet seat, as this represents the direct user contact area. Each toilet seat was swabbed on three locations: the rear, left and right parts of the seat. The swab testing was then undertaken by an independent NATA (National Association of Testing Authorities) accredited laboratory.*

In conjunction with the swab testing, visual assessments were undertaken during field visits. The toilets were inspected for cleanliness and given a score  between 1 and 5 (1 being very clean, and 5 being very dirty).

During the assessment, two service teams undertook to either empty, clean and/or service the portable toilets as per normal routine procedures utilised at Aim Hire. Thirty of the portable toilets had their tanks emptied and the toilets were cleaned and serviced. Immediately after,  they were swabbed for microbiological analysis. The purpose of this was to assess the baseline measurement of bacteria levels in toilets that had just been emptied and cleaned.

These same toilets were then visited 14 days later and swabbed for analysis and assessed for visual cleanliness. This data was compared to the first survey to assess the level of change in microbiology and the hygiene status of these toilets having been used for 14 days.

A third test was carried out on 24 toilets that had not had their sewage tanks emptied for 30 days or more. These toilets were cleaned but their tanks were not emptied. After 14 days, these toilets were revisited, swabbed and assessed visually for cleanliness. This study was undertaken to assess whether the relative fullness of the tanks contributed to any microbiological or hygiene differences compared to toilets that had their tanks emptied at the start of the test period.

All test results were analysed and compared by Sharpe and Howell and the conclusions tabled. According to Dr Comar, while it is a commonly held view that toilets, and in particular public toilets, pose some form of health risk, this is largely scientifically unfounded. “The evidence to support transmission of disease directly from toilet is virtually non existent. The public perception of risk is disproportionate to the reality”, said Comar.

“This study has shown that the risk of any significant contamination coming from a toilet seat, the direct user contact area, is very low. Toilets in the field  and in use for two weeks showed no significant increases in microbial loadings to the toilets seats compared to when they were freshly cleaned. Some deterioration in appearance was experienced over the 14 days, but this was not materially translated into higher microbial numbers”, concluded Dr Comar.

It was also proven by Comar that the status of the tanks had no significant impact on the hygiene of the toilet. Dr Comar concluded that there is no scientific reason to support an arbitrary prescriptive timeframe for emptying tanks. In other words, there is no scientific reason to empty portable toilet sewage tanks other than when they are full.

While it was clearly demonstrated that these particular toilets posed no direct concern for public health, it should be noted that  the most important thing to do when using a public or portable toilet, is to wash ones hands. Comar says there is considerable evidence that the human hand as a vector in the transmission of disease is an important factor. “Most of the significant diseases require the faecal-oral route for transmission, hence the importance of hand washing”, says Comar.

The US Centre for Disease Control and Prevention recommends washing hands in clean water and soap for at least 20 seconds post toilet to prevent the spread of germs.

So next time you need to use your portable site toilet, no need to cringe. Your bottom is safe for seating!

To read the full report by Sharpe and Howell, visit the Servicing section of the Aim Hire web site at


1.       Charles P. Gerba, Craig Wallis & Joseph Melnick, Dept of Virology and Epidemiology, Baylor College of Medicine, Houston, Texas, Microbioligicl  Hazards of Household Toilets: Droplet Production and the Fate of Residual Organisms, Aug. 1975

2.       Dr Derio Comar, BSc (Hons), FRACI, MASM, MAIFST, Consulting Microbiologist, Hygiene Study of Portable Toilets Used at Single Dwelling Construction Sites, March 2011.

3.       Microbiological testing undertaken by Silliker Australia Pty Ltd

Keywords: Portable Toilets, Toilets