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When you’re a patient in a hospital, you’d like to think the doctors, nurses, or orderlies standing at your bedside had recently washed their hands, wouldn’t you?

You’d also probably be glad to hear that hospitals in recent years have pushed for more hand-washing stations — part of an effort to cut down on the spread of bacteria that thrive in hospitals, further compromising the health of people who are already sick.

There’s a problem here, however. Those sinks have been implicated in the spread of dangerous bacteria.


In a devilish case of unintended consequences, sinks have been linked to a number of outbreaks of serious infections in hospitals from Baltimore to Shanghai and many places in between in recent years. In one notable case, a hospital in the Netherlands took sinks out of the patient rooms in its intensive care unit in a bid to slow the spread of bacteria. (It worked.)

At a time when concern is mounting about antibiotic resistance, and when the specter of untreatable infections threatens the advances of modern medicine, finding ways to slow the development and spread of drug-resistant bacteria is a major preoccupation of infection control teams. As a result, evidence that hospital sinks could exacerbate the problem presents health care specialists with a quandary.


“The thing about the sinks is that they’re the cornerstone of infection control policy. … All of the [hospital] guidelines in the developed world talk about having sinks — the ratio of sinks per beds and where they are and that sort of thing,” said Dr. Michael Gardam, director of infection control at University Health Network, an institution comprising four Toronto hospitals.

When it comes to hospital sinks, there are two major issues.

First, the water coming into them can contain bacteria. That’s true of any sink, anywhere; municipal water treatment systems don’t produce sterile water. But a bug that isn’t a risk for a healthy person can be dangerous for someone whose immune system is suppressed to prevent rejection of a donor organ or who is recuperating from a serious operation.

The other problem is that sinks, particularly the pipes that drain them, are ideal places for bacteria to proliferate. The bugs form what are known as biofilms – colonies where they gang together and attach to a surface. These water-dwelling bacteria especially like p-traps, the U-shaped bend in pipes that drain the contents of a sink.

Getting rid of biofilms once they form is, well, pretty much impossible. There are cleaning tricks hospitals try, but even those generally only lower the bacterial count for a while.

“Once you have the biofilms in there, short of ripping the sinks and the piping out, it’s impossible to get rid of. And in fact, even if you do that, it frequently comes back,” said Dr. Alex Kallen, a medical officer in the Center for Disease Control and Prevention’s division of health care quality promotion.

He said it’s not entirely clear how much of a risk biofilms in hospital sinks pose. These bacterial colonies are generally — though not always — found in the pipes leading away from sinks, so people using the sinks shouldn’t, in theory, have contact with them.

In fact, to see if bacteria from biofilms in sinks drains could find their way back up to contaminate hands, the CDC ran an experiment where it had people wash their hands in sinks with contaminated drains. It saw no evidence of bacteria transferring from sinks to hands.

But Kallen said more experiments are underway because of the number of reports that put sinks squarely at the heart of hospital outbreaks.

Gardam has firsthand experience with an outbreak caused by a sink. It was a bad one. Three dozen patients in intensive care contracted a drug-resistance bacteria; an investigation after the fact said five died because of the infection.

“Once you have the biofilms in there, short of ripping the sinks and the piping out, it’s impossible to get rid of.”

Dr. Alex Kallen, CDC

Figuring out how the patients were getting infected took sleuthing, but eventually suspicion fell on some sinks in the ICU. They had gooseneck faucets that directed water straight down into the drain. The pressure created back splash, with tiny droplets of bacteria-laced water spraying onto nearby porous surfaces where medical staff prepared tubing and other equipment used in patient care.

Gardam ordered staff to stop using the sinks, going so far as encasing them in garbage bags. There were no new cases after that.

The hospital subsequently made a number of changes, which have been adopted elsewhere as well, Gardam said.

“Some of the stuff we’ve learned … is: Don’t have the gooseneck (faucet) drain directly into the drain; have it drain off the side of the bowl. Don’t allow it to splash. Make sure it’s deep enough that it can’t splash on you and splash on your clothing. Make sure that the stuff around [the sinks] is waterproof.”

Exacerbating the problem is the fact that biofilms that develop in hospital sinks may house really bad bugs – bacteria that are resistant to key antibiotics. That’s because sinks aren’t just used to wash hands. Staff sometimes use them to dispose of patient specimens – urine, for instance – or to drain the dregs of an intravenous bag of antibiotics.

“It’s just like: How do you use your kitchen sink? You dump your disgusting stuff down there and then you wash your hands,” said Dr. Trish Perl, an infection control expert who is chief of infectious diseases at the University of Texas Southwestern Medical Center in Dallas.

Hospitals should have clean sinks — for hands — and dirty sinks, for disposing of patient specimens, said Kallen. But some health care workers would argue it’s safer to tip a specimen into the nearest sink rather than walk down a hallway with something that might spill.

“There does seem to be at least anecdotal evidence that if you discard patient specimens down sinks, then you can contaminate the drains with the things that are in those specimens — which, if they’re in the hospital, are more likely to be multidrug resistant [organisms],” said Kallen.

“Now whether or not that’s a true source of transmission to other patients is controversial. But you certainly can contaminate the sink that way.”

As problems with sinks have become apparent, experts have been working to design better and safer sinks.

The superbugs are growing in number and strength. Hyacinth Empinado/STAT

But even there it’s important to look for unintended consequences. For instance, a couple of studies, including one done by Perl, looked at bacterial accumulation in electronic eye faucets — the no-tap sinks where water flow is activated by placing hands in front of a sensor.

The suspicion is that sinks without taps would actually reduce the risk that freshly washed hands would be recontaminated by turning off taps. But some appear to be more likely to accumulate bacteria, Perl said, explaining they have multiple internal valves and more surfaces on which biofilms can form.

It’s an important lesson, she said: New sink designs need to be tested, in the way drugs are, to ensure they are actually better.

“We need to start insisting on studies so that we understand the implications of introducing novel technologies before we do it,” she said.

Health care specialists say concerns about hospital sinks have provided them with another lesson: Use alcohol gel. Some people still believe it dries out their skin, and it’s not effective on its own if a health care worker’s hands are soiled.

But there’s no doubt that it can help curb the spread of bacteria. And it is, in fact, what the CDC recommends when hands need to be cleaned but aren’t soiled with a contaminant that gel won’t remove.

“But you know, the cornerstone of hand washing isn’t sinks, it’s alcohol gel,” said Gardam. “And the reason why the world has moved to alcohol gel is that it’s a lot cheaper, it works better, it’s faster, you can wash your hands while you’re walking, it doesn’t dry your hands out as much. I can go on and on and on.”

  • Aequor is a small company that has developed proprietary novel molecules that remove existing biofilm and prevent its formation. We can’t find investors who understand why this is important!
    Biofilm in hospitals is everywhere — not only in sinks. It is on every surface (ceilings, walls, curtains, bed rails, floors, etc.). Patient deaths from AMR strains were even traced to tie worn by the doctor who made the rounds.
    Regarding water and air systems, biofilm resists removal by every known biocide at non-lethal doses. Pouring bleach down a sink may not be effective, as chemicals in biofilms’ top layers neutralize the harshest biocides. Physical scraping works, but is short-term.
    Biofilm builds and then sloughs off and spreads in air and water. Readers may recall from Legionnaire’s disease, deaths were traced by biofilm in the air system and shower heads that became aerosoled and inhaled by the victims.

    Aequor’s Founder, Cynthia Burzell, is an expert in biofilm. She offers biofilm testing to see if what is being used is effective and has compiled a database showing what is known not to work.
    We will lose the war on bacteria and continue triggering further resistance unless we use the proper tools to remove the biofilm so that the human immune system, biocides and antibiotics can kill the underlying free-floating bacteria, which is the only thing that they were designed to do.

  • In our hospital, we’re trained not to touch the sink, especially the drain portion once we’ve washed our hand. Would be great to actually see how biofilms from the U-Bend travel upwards through the pipe onto someone’s hands post wash, especially as these sinks are usually knee operated. We’ve installed cameras above our sinks and sanitizer dispensers, but thankfully we have not had such cases, seems like this would make for a great case study.

    Secondly, how does pouring bleach down the sink nightly, a common practice, not sterilize the U-Bend?

  • Re: Helen Branswell’s article about the dangers of hospitals sinks (Oct 25): It is very surprising to see a hospital infection control officer (a certain Dr. Gardam, from Toronto) being quoted as saying that “the cornerstone of hand washing isn’t sinks, it’s alcohol gel.” This statement is misleading at best, and for certain organisms in the hospital setting, it is completely wrong. Alcohol-based hand gels have many advantages, as the article pointed out, but still do not eradicate certain viruses such as norovirus – nor are they effective against sporulated bacteria such as C. difficile (hand washing, 30 sec. under running water, is the only way). Both of these bugs are very common, and cause enormous problems in hospitals.

  • Reasons for Contaminated Water Systems
    There are many reasons why a water system can become contaminated with pathogens such as Legionella or Pseudomonas. It is likely that the pathogens are already in any water system, but at low concentrations where they will not have any effect on health. Problems arise when the pathogens are able to reach high concentrations and where there is also an exposure route.

    The reasons that contamination occurs in the pipework can include water temperatures, over-sized pipework (or other installation mistakes), long travel distances, long stagnation phases, short circuits in the cold water/warm water system, dead legs, not enough thermal disinfection, retrograde contamination or simply a growing bio-film colony in the hot and cold water systems. The age of the system is one of the less important factors, though the older the system the higher the chance for dead legs and areas of stagnation. In addition the piping materials have an influence on the speed and extent of bacterial colonisation i.e. iron is a source of nutrients for bacteria and is a good growing medium for biofilm, copper is mildly phytotoxic and plastic makes a good base for biofilm.

    Biofilm, Legionella and Pseudomonas
    In the case of biofilm, it forms in places with a high count of different micro-organisms (bacteria, fungi, eukaryotes), which settle and bond to surfaces that are wet (for example pipes and boilers). These micro-organisms are usually covered by a film of mucous substance, that are produced by the micro-organisms, these are embedded together and fixed at the surfaces (think of the slime feel in some hot tubs or pools). The mucous substances, which can form up to 90 % of the biofilm, contain other diluted and particulated products (for example corrosion by-products, scale etc) which are nutrients for the organisms. When touched, the biofilms have the feel of a thin film of slime.

    Biofilms are potentially a risk area for infections, because in general bacteria find biofilms an ideal breeding ground. Water treatment can only ever be fully successful if the treatment method used either reduces biofilm or prevents its build up. If you can take away the breeding ground for the micro-organisms on a continuous basis then you can increase the overall hygiene of the water. It is worth noting that Legionella does not form a primary biofilm, it colonises areas where a biofilm already exists.

    The general insight gained through the German BMBF- joint project “biofilm in drinking water installations” can be summarised as the follows:

    Drinking water is not sterile and should not be. In general the water suppliers deliver a very stable drinking water this is largely due to due to the low nutritional content of the water, the water therefore generally passes the microbiologic requirements for drinking water. Nevertheless bacteria often enter into a domestic installation. When the bacteria find nutrition in the domestic installation, then they can occupy the wet surfaces and lead to a build up of biofilm. The extent of a biofilm build up is influenced by various factors. The biological nutriton content and the water temperatures are the deciding factors. With an increase in the nutritional content and an increase in water temperature the biofilm build up increases. The intensity of the biofilm is also dependent of the pipe material and their age. Some new polymer pipes can contain biologically usable additives like softener, anti-oxidation materials and release agents, which can serve as a nutritional source. On new materials you can have biofilm a build up in one to two weeks, and after a few more weeks you reach a quasi steady state.

    Source: BMBF (Bundesministerium für Bildung und Forschung) Contamination in cold water systems.

    If biofilm is present then it is impossible to have a microbially hygienic water system.

    How the Aquadron Addresses Biofilm
    The Aquadron treats all of the water that passes through the system, it does this by proportionally dosing all of the water with Anolyte, 24 hours a day, seven days a week. The Anolyte passes through the whole system, removing biofilm and killing bacteria, it even works in the shower heads and taps, at a point that is beyond the thermal mixing valves and that is not protected by thermal treatment. This ensures that bacterial colonies can not form in the pipework system.

    Once the system has been disinfected it is possible to operate without the thermal barrier, this means that water temperatures can be reduced. This saves energy and money – the net effect is that you get improved water treatment with far higher levels of safety and energy savings pay for the system. Additional information and case studies available at

  • This is an excellent topic of relevance to all in infection control and healthcare. Unfortunately, the solution is so blindingly obvious that it is ignored as being too simple by engineers and facility managers and the chemical industry keeps on telling people to pour their products down the sink (which has never really worked and is only part of the solution).
    Research at the University of Dublin, Trinity College has developed effective and consistent infection controls for water systems and sinks by addressing some of the most difficult biofilm scenarios – dental chair waterlines and suction systems – and then progressing to taps and sinks. The efficacy is undisputed, the savings in chemicals and labour, immense and real life implementation in a number of international dental hospitals has been undertaken. As a result, sterile water enters dental patients’ mouths, suction systems are no longer contaminated, water from taps is usually sterile and sinks and their waste pipes and U-bends are also virtually sterile. The systems are now automated and can be installed realtively easily. Systems are providing water line protection in about 10 major dental hospitals globally and have been so for around 8 years. The systems have been extended to water supplies to sinks in a number of these and now the automated disinfection of the sinks and their wastepipes is being implemented. This is also being introduced in a major acute hospital also.
    Dublin University Dental Hospital has such systems running for over 9 years and has published extensively on implementation and performance. Here are some papers of relevance to the subject:-

    J.S. Swan , E.C. Deasy , M.A. Boyle , R.J. Russell , M.J. O’Donnell , D.C. Coleman Elimination of biofilm and microbial contamination reservoirs in hospital washbasin U-bends by automated cleaning and disinfection with electrochemically activated solutions. Journal of Hospital Infection 94, 169-174 2016
     M.A. Boyle , M.J. O’Donnell , A. Miller , R.J. Russell , D.C. Coleman Control of bacterial contamination of washbasin taps and output water using Ecasol: a one-year study. Journal of Hospital Infection (2012) 80, 288-292
    Hota S, Hirji Z, Stockton K, et al. Outbreak of multidrug-resistant Pseudomonas aeruginosa colonization and infection secondary to imperfect intensive care unit room design. Infect Control Hosp Epidemiol 2009; 30:25-33.
    Decker BK, Palmore TN. The role of water in healthcare-associated infections. Curr Opin Infect Dis 2013; 26:345-351.
    Roux D, Aubier B, Cochard H, Quentin R, van der Mee-Marquet N; HAI Prevention Group of the Re´seau des Hygie´nistes du Centre. Contaminated sinks in intensive care units: an underestimated source of extended-spectrum beta-lactamase-producing Enterobacteriaceae in the patient environment. J Hosp Infect 2013;85:106-111.
    Breathnach AS, Cubbon MD, Karunaharan RN, Pope CF,Planche TD. Multidrug-resistant Pseudomonas aeruginosa outbreaks in two hospitals: association with contaminated hospital waste-water systems. J Hosp Infect 2012;82:19-24.
    Starlander G, Melhus A° Minor outbreak of extended-spectrum blactamase-producing Klebsiella pneumoniae in an intensive care unit due to a contaminated sink. J Hosp Infect 2012;82:122-124.
    Loveday HP, Wilson JA, Kerr K, Pitchers R, Walker JT, Browne J. Association between healthcare water systems and Pseudomonas aeruginosa infections: a rapid systematic review. J Hosp Infect 2014;86:7-15.
    M.I. Garvey*, C.W. Bradley, J. Tracey, B. Oppenheim Continued transmission of Pseudomonas aeruginosa from a wash hand basin tap in a critical care unit J Hosp Infect 2016; In Press
    Soothill JS. Carbapenemase-bearing Klebsiella spp. in sink drains: investigation into the potential advantage of copper pipes. J Hospital Infection 2016; 93:152-154.
    Cholley P, Thouverez M, Floret N, Bertrand X, Talon D. The role of water fittings in intensive care rooms as reservoirs for the colonization of patients with Pseudomonas aeruginosa. Intensive Care Med 2008;34:1428-1433.
    Fusch C, Pogorzelski D, Main C, Meyer C-L, el Helou S, Mertz D. Self-disinfecting sink drains reduce the Pseudomonas aeruginosa bioburden in a neonatal intensive care unit. Acta Paediatr 2015;104:e344-349.
    O’Donnell MJ, Boyle M, Swan J, Russell RJ, Coleman DC. A centralised, automated dental hospital water quality and biofilm management system using neutral Ecasol maintains dental unit waterline output at better than potable quality: a 2-year longitudinal study. J Dent 2009;37:748-762.
    J.S. Brooke Pathogenic bacteria in sink exit drains J Hospital Infection, Volume 70, Issue 2, October 2008, Pages 198-199

  • Aequor has developed a portfolio of over 40 novel, non-toxic, “green” chemicals that remove biofilm and prevent its formation on industrial/clinical surfaces and on human/animal tissues.
    Biofilm has been well-studied since 1995 and the CDC has had a Biofilm Lab for the last 10 years. As they well know, almost all medically-relevant bacteria form biofilm to protect themselves from the human immune system, biocides (disinfectants, antimicrobials, antiseptics) and antibiotics. As was known from Legionnaire’s disease, biofilm forms in water systems (sinks, shower heads, pipes, filters) becomes aerosoled and can be inhaled. Biofilm is also found on all surfaces in a hospital: ceilings, floors, walls, bedding, bedrails, etc. — as well as oxygen supplies, scopes, devices, etc. etc. One HAI was traced to a doctor’s necktie, as he made his rounds, even though we was wearing a clean lab coat.

    Biofilm can be easily removed with the right chemicals. The current biocides and antibiotics just trigger the formation of thicker biofilm. UV and sterilization work, but are short-term remedies. Biofilm was recorded on a titanium plate within 30 seconds of sterilization. Copper and silver are natural antimicrobials, but have also shown to be ineffective over time.

    Please see for more info. Please take advantage of our biofilm testing and educational services to evaluate the efficacy of the remedies you are trying.

  • Materials can make a difference to patient safety – The evidence regarding copper and copper alloys having much lower microbial bioburden than standard materials used in clinical settings is impressive.
    You can now get sinks made from copper alloys that resemble stainless steel but which rapidly and continuously kill bacteria, viruses yeasts and fungi.
    For info on copper’s efficacy, see

  • the whole article is alarming and message is well addressed. But my concern is that I have read an article a week ago that some antibacterial soaps have been banned from the market, according to findings by FDA that they are main cause of AMR. and now here I read that hospital sinks are contributing a lot, the way we use antibiotics specially in under developed countries like mine is not rational. These all being added together will definitely cause a disastrous impact in global health. My comment on this article is basic and simple. What if we plant the sinks out side of the rooms where patients are, so that cross contamination is avoided, that is to say health care professionals (and care givers) get to scrub their hands out of the patients room, and use alcohol gel for the patients sanitation purpose. Drying of hands will not be a problem (if it really is) as the patients stay in the hospital temporarily. for me it seems getting the sinks out of the patient area is the only solution for problems of this kind.

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