How To Treat Legionella In Water?

How To Treat Legionella In Water
Chemical shock using an elevated level of a disinfectant, such as chlorine, for a limited duration can control Legionella in a potable water system.

Contents

What happens if Legionella is detected in water?

But take it seriously – Growth of legionella bacteria in a water system can lead to a risk of people contracting Legionnaires’ disease. This is a serious form of pneumonia that can have fatal consequences, as well as severe financial and legal repercussions for an organisation responsible for an outbreak.

Take action to protect the health and safety of the people in your care (staff, residents, visitors, etc); Notify the relevant bodies.

Can you flush out Legionella?

Removing or flushing infrequently used taps can significantly reduce the risk of legionella. Where? All infrequently used taps must be flushed, including taps found within fume cupboards.

How do you disinfect Legionella?

Use water with free chlorine at a minimum concentration of 5 parts per million (ppm) to remove any biofilm (slime). After scrubbing, rinse the tub with clean water and flush to waste.

How is Legionella cured?

Treatment and Complications – Legionnaires’ disease requires treatment with antibiotics and most cases of this illness can be treated successfully. Healthy people usually get better after being sick with Legionnaires’ disease, but they often need care in the hospital. Possible complications of Legionnaires’ disease include

  • Lung failure
  • Death

About 1 out of every 10 people who gets sick with Legionnaires’ disease will die due to complications from their illness.1 For those who get Legionnaires’ disease during a stay in a healthcare facility, about 1 out of every 4 will die.2

What temperature kills Legionnaires in water?

Notes. Hot water should be stored at 60 °C at least in order to kill legionella bacteria.

Can you drink water with Legionella?

How It Spreads – After Legionella grows and multiplies in a building water system, water containing Legionella can spread in droplets small enough for people to breathe in. People can get Legionnaires’ disease or Pontiac fever when they breathe in small droplets of water in the air that contain the bacteria.

  1. Less commonly, people can get sick by aspiration of drinking water containing Legionella,
  2. This happens when water accidently goes into the lungs while drinking.
  3. People at increased risk of aspiration include those with swallowing difficulties.
  4. In general, people do not spread Legionnaires’ disease and Pontiac fever to other people.

However, this may be possible under rare circumstances.1

  • You believe you were exposed to Legionella AND
  • You develop symptoms, such as fever, cough, chills, or muscle aches

Your local health department can determine whether to investigate. Be sure to mention if you spent any nights away from home in the last 14 days.

How long should you flush a tap for Legionella?

The five-minute flush – Whenever a property is to be left unused for a time, weekly flushing is a good way to reduce the chances of any problems cropping up. It is easy to do and requires only a small amount of time. Each tap and water outlet (including showers) should be opened and left to run through for at least five minutes.

DIY test for legionella – quick and easy, no prior expertise with results in 25 mins

The shower should be turned up so it’s as hot as possible. It’s important to remember that your hot and cold water temperatures should achieve the following:

Hot water – a minimum of 50 degrees Celsius after one minute (55 degrees Celsius in healthcare settings). With a TMV fitted, water temperatures at the hot tap should not exceed 44 degrees Celsius. Cold water – a maximum of 20 degrees Celsius or below after two minutes.

How do you get rid of Legionella in the shower?

Using temperature control – The primary method used to control the risk from Legionella is water temperature control. Water services should be operated at temperatures that prevent Legionella growth:

Hot water storage cylinders (calorifiers) should store water at 60°C or higher Hot water should be distributed at 50°C or higher (thermostatic mixer valves need to be fitted as close as possible to outlets, where a scald risk is identified). Cold water should be stored and distributed below 20°C.

A competent person should routinely check, inspect and clean the system, in accordance with the risk assessment. You must identify ‘sentinel’ outlets (furthest and closest to each tank or cylinder) for monthly checking of the distribution temperatures.

You should also check the hot water storage cylinder temperatures every month and cold water tank temperatures at least every six months. Stagnant water favours Legionella growth. To reduce the risk you should remove dead legs/dead ends in pipe-work, flush out infrequently used outlets (including showerheads and taps) at least weekly and clean and de-scale shower heads and hoses at least quarterly.

Cold-water storage tanks should be cleaned periodically and water should be drained from hot water cylinders to check for debris or signs of corrosion. Design systems to minimise Legionella growth, by:

keeping pipe work as short and direct as possible; adequately insulating pipes and tanks; using materials that do not encourage the growth of Legionella; preventing contamination, eg by fitting tanks with lids and insect screens.

How long do I run a shower for Legionella?

How often should you run a shower to prevent Legionella? – Legionella bacteria can build up in any shower, tap, or water outlet that is not used regularly as the water in the system remains stagnant. When turned on, bacteria will flow out of the system with water, and whoever is using the shower will breathe in aerosols containing Legionella bacteria.

This is a greater concern in hotels and offices, for example, where showers and taps may go unused for prolonged periods. However, even in homes, any guest bathroom could be at risk. It is advisable to run any infrequently used showers or taps for about two minutes each week or until the hot and cold water are the same temperature as frequently used outlets.

Make sure to leave the room to avoid potentially breathing in aerosols containing Legionella bacteria.

Is Legionella killed by chlorine?

Susceptibility of Legionella pneumophila to chlorine in tap water. A study was conducted to compare the susceptibility of legionellae and coliforms to disinfection by chlorine. The chlorine residuals used were similar to concentrations that might be found in the distribution systems of large public potable water supplies.

The effects of various chlorine concentrations, temperatures, and pH levels were considered. A number of different Legionella strains, both environmental and clinical, were tested. The results indicate that legionellae are much more resistant to chlorine than are coliform bacteria. At 21 degrees C, pH 7.6, and 0.1 mg of free chlorine residual per liter, a 99% kill of L.

pneumophila was achieved within 40 min, compared with less than 1 min for Escherichia coli. The observed resistance is enhanced as conditions for disinfection become less optimal. The required contact time for the removal of L. pneumophilia was twice as long at 4 degrees C than it was at 21 degrees C.

These data suggest that legionellae can survive low levels of chlorine for relatively long periods of time. Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the (869K), or click on a page image below to browse page by page. Links to PubMed are also available for,

These references are in PubMed. This may not be the complete list of references from this article.

Bopp CA, Sumner JW, Morris GK, Wells JG. Isolation of Legionella spp. from environmental water samples by low-pH treatment and use of a selective medium. J Clin Microbiol.1981 Apr; 13 (4):714–719. BRAZIS AR, LESLIE JE, KABLER PW, WOODWARD RL. The inactivation of spores of Bacillus globigii and Bacillus anthracis by free available chlorine. Appl Microbiol.1958 Sep; 6 (5):338–342. Public Health Weekly Reports for DECEMBER 17, 1943. Public Health Rep.1943 Dec 17; 58 (51):1837–1880. Cherry WB, Pittman B, Harris PP, Hebert GA, Thomason BM, Thacker L, Weaver RE. Detection of Legionnaires disease bacteria by direct immunofluorescent staining. J Clin Microbiol.1978 Sep; 8 (3):329–338. Cordes LG, Wiesenthal AM, Gorman GW, Phair JP, Sommers HM, Brown A, Yu VL, Magnussen MH, Meyer RD, Wolf JS, et al. Isolation of Legionella pneumophila from hospital shower heads. Ann Intern Med.1981 Feb; 94 (2):195–197. Dennis PJ, Taylor JA, Fitzgeorge RB, Bartlett CL, Barrow GI. Legionella pneumophila in water plumbing systems. Lancet.1982 Apr 24; 1 (8278):949–951. England AC, 3rd, Fraser DW, Mallison GF, Mackel DC, Skaliy P, Gorman GW. Failure of Legionella pneumophila sensitivities to predict culture results from disinfectant-treated air-conditioning cooling towers. Appl Environ Microbiol.1982 Jan; 43 (1):240–244. Fisher-Hoch SP, Bartlett CL, Tobin JO, Gillett MB, Nelson AM, Pritchard JE, Smith MG, Swann RA, Talbot JM, Thomas JA. Investigation and control of an outbreaks of legionnaires’ disease in a district general hospital. Lancet.1981 Apr 25; 1 (8226):932–936. Fliermans CB, Cherry WB, Orrison LH, Thacker L. Isolation of Legionella pneumophila from nonepidemic-related aquatic habitats. Appl Environ Microbiol.1979 Jun; 37 (6):1239–1242. Grace RD, Dewar NE, Barnes WG, Hodges GR. Susceptibility of Legionella pneumophila to three cooling tower microbicides. Appl Environ Microbiol.1981 Jan; 41 (1):233–236. Jarroll EL, Bingham AK, Meyer EA. Effect of chlorine on Giardia lamblia cyst viability. Appl Environ Microbiol.1981 Feb; 41 (2):483–487. Pasculle AW, Feeley JC, Gibson RJ, Cordes LG, Myerowitz RL, Patton CM, Gorman GW, Carmack CL, Ezzell JW, Dowling JN. Pittsburgh pneumonia agent: direct isolation from human lung tissue. J Infect Dis.1980 Jun; 141 (6):727–732. Rice EW, Hoff JC, Schaefer FW., 3rd Inactivation of Giardia cysts by chlorine. Appl Environ Microbiol.1982 Jan; 43 (1):250–251. Skaliy P, Thompson TA, Gorman GW, Morris GK, McEachern HV, Mackel DC. Laboratory studies of disinfectants against Legionella pneumophila. Appl Environ Microbiol.1980 Oct; 40 (4):697–700. Stout J, Yu VL, Vickers RM, Zuravleff J, Best M, Brown A, Yee RB, Wadowsky R. Ubiquitousness of Legionella pneumophila in the water supply of a hospital with endemic Legionnaires’ disease. N Engl J Med.1982 Feb 25; 306 (8):466–468. Tobin JO, Bartlett CL, Waitkins SA, Barrow GI, Macrae AD, Taylor AG, Fallon RJ, Lynch FR. Legionnaires’ disease: further evidence to implicate water storage and distribution systems as sources. Br Med J (Clin Res Ed) 1981 Feb 14; 282 (6263):573–573. Tobin JO, Beare J, Dunnill MS, Fisher-Hoch S, French M, Mitchell RG, Morris PJ, Muers MF. Legionnaires’ disease in a transplant unit: isolation of the causative agent from shower baths. Lancet.1980 Jul 19; 2 (8186):118–121. Wadowsky RM, Yee RB. Glycine-containing selective medium for isolation of Legionellaceae from environmental specimens. Appl Environ Microbiol.1981 Nov; 42 (5):768–772. Wadowsky RM, Yee RB, Mezmar L, Wing EJ, Dowling JN. Hot water systems as sources of Legionella pneumophila in hospital and nonhospital plumbing fixtures. Appl Environ Microbiol.1982 May; 43 (5):1104–1110. Wang WL, Blaser MJ, Cravens J, Johnson MA. Growth, survival, and resistance of the Legionnaires’ disease bacterium. Ann Intern Med.1979 Apr; 90 (4):614–618. Yee RB, Wadowsky RM. Multiplication of Legionella pneumophila in unsterilized tap water. Appl Environ Microbiol.1982 Jun; 43 (6):1330–1334.

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How long does Legionella take to develop in water?

Bacteria when in ideal conditions will grow, if you put legionella on an agar plate and incubate it for 7 – 10 days with a temperature range of between 20˚C and 50˚C, a colony will form of millions of bacteria that you will be able to see.

What is the most common way of contracting Legionella?

How the infection spreads – Most people become infected when they inhale microscopic water droplets containing legionella bacteria. This might be from the spray from a shower, faucet or whirlpool, or water from the ventilation system in a large building. Outbreaks have been linked to:

Hot tubs and whirlpools Cooling towers in air conditioning systems Hot water tanks and heaters Decorative fountains Swimming pools Birthing pools Drinking water

Besides by breathing in water droplets, the infection can be transmitted in other ways, including:

Aspiration. This occurs when liquids accidentally enter your lungs, usually because you cough or choke while drinking. If you aspirate water containing legionella bacteria, you can develop Legionnaires’ disease. Soil. A few people have contracted Legionnaires’ disease after working in a garden or using contaminated potting soil.

What antibiotic kills Legionella?

Treatment for Legionnaires’ Disease – Treatment recommendations for LD are generally based on clinical experience with the first recognized breakout in Philadelphia in 1976.8 In a retrospective review, patients treated with erythromycin or tetracycline had a 50% lower mortality rate compared with patients treated with beta-lactam antibiotics.9 The choice of antibiotic is often dependent on the patient’s clinical state, the risk of adverse drug interactions and tolerance to the medication, and the degree of certainty as to the diagnosis. Macrolides except azithromycin can interact with drugs metabolized by the CYP3A4 isoenzyme (e.g., cyclosporine). Unlike the 14-member macrolides previously mentioned, the 15-member lactone ring of azithromycin does not interact with the CYP3A4 isoenzyme.

Macrolides also have the potential to induce QT-interval prolongation syndrome; the rank (from highest to lowest) for this interaction is erythromycin, clarithromycin, roxithromycin, and azithromycin.12,13 The quinolones mentioned above do not inhibit CYP3A4 and are suitable drugs to treat LD in patients taking cyclosporine or other CYP3A4 substrates.

An older fluoroquinolone, ciprofloxacin, inhibits CYP3A4 and may have limited use because the FDA has not approved fluoroquinolones for persons younger than 18 years (because of concerns about arthropathy in studies of juvenile animals), but they have been successfully used to treat children with LD.14-16 Doxycycline may cause some relatively minor gastrointestinal (GI) issues, but it may make exposed skin more sensitive to the sun.

Patients should avoid prolonged sun exposure, tanning booths, and sunlamps, and use a sunscreen when exposed to longer periods of direct sunlight. Beta-lactam antibiotics are not included because they do not penetrate Legionella ‘s intracellular compartment; therefore, they are not considered effective agents.8 Generally, azithromycin has been shown to be more active and is considered the drug of choice because it has high intracellular compartment penetration to kill the bacteria and may be used in adults and children.17-20 Azithromycin is particularly effective because of decreased GI irritation, higher potency, better intracellular penetration into tissue, and once-daily dosing.18,21 Severe cases of LD may be resistant to a single antibiotic.

In these cases, a second drug such as rifampin may be added because rifampin is very active against extracellular and intracellular Legionella species.8,21-27 Although LD may present as a mild illness called Pontiac fever, this condition usually requires no specific antibiotic treatment.

However, many patients with LD require hospitalization to receive parenteral antibiotics and fluids to treat the infection and prevent and/or treat dehydration or septic shock.3 Most healthy patients show clinical improvement within 3 to 5 days after antibiotic therapy begins. A delay in getting appropriate treatment significantly increases the risk of mortality in LD.

Therefore, empirical anti- Legionella therapy is initiated promptly to treat severe community-acquired and nosocomial pneumonias. A study by van Loenhout et al, which included 190 patients with LD, found that a year after the disease’s onset, many patients were still suffering from one or more adverse health effects, particularly fatigue and reduced general quality of life.28 Most nosocomial infections and hospital outbreaks have been linked to a contaminated hot and/or cold water supply.29 Nosocomial LD associated with water birth is reported in a few neonates, but the risk appears to be low.30,31 Person-to-person transmission has not been demonstrated.

Where is Legionella most likely to be found?

Where does it come from? – Legionella bacteria are widespread in natural water systems, eg rivers and ponds. However, the conditions are rarely right for people to catch the disease from these sources. Outbreaks of the illness occur from exposure to legionella growing in purpose-built systems where water is maintained at a temperature high enough to encourage growth, eg cooling towers, evaporative condensers, hot and cold water systems and spa pools used in all sorts of premises (work and domestic).

What level of chlorine kills Legionella?

I received an e-mail from an industry leader in water conservation asking about a recent column on Legionnaires Disease. The column mentioned that water conservation efforts were contributing to Legionella incidents without explaining how water treatment chemicals (Chlorine) dissipates in the municipal and building water systems.

  • He asked me to explain how this happens, so I thought it would be best to explain it to everyone in this column.
  • When low-flow fixtures and water conservation efforts are enacted, the flow of water is reduced, but the water mains must still be sized to handle fire flows.
  • The reduction in flow causes the water stay in the piping system three to four times longer than prior to 1992, when the energy policy act was enacted.

The slower water flow allows water treatment chemicals to dissipate to lower levels by the time the water gets to the remote portions of the water distribution systems. This phenomenon is known chlorine dissipation or some people are calling it “aged water” or “stagnant water.” The water treatment process The water treatment process draws source water in from a well, lake, stream or river.

A coagulant is added to remove dirt and other particles suspended in water. Chemicals, such as aluminum and iron salts, are added to the raw water to form tiny sticky particles called “floc” known as a flocculation process. Flocculation acts as a magnet and attracts other dirt particles. The combined weight of the dirt and flocculants become heavy enough to sink to the bottom of settling basins during the clarification process.

During the clarification process, the heavy particles (flocculants) settle out in settling basins and are removed and the clear water moves on to sand filtration beds. Filtration occurs when the water passes through layers filters, that consist of some made of layers of sand, gravel and activated carbon, which help remove even smaller particles.

  • The next step is the disinfection process, where a small measured amount of chlorine, monochlorine or Chlorine Dioxide is added to kill any bacteria, amoebas and other organic pathogens in the water system.
  • After the Chlorine or other water treatment chemical is added, the water is transferred to a holding tank or basin to provide ample contact time for disinfection to occur.
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Most municipal water systems have large storage tanks, where treated water is stored until it is needed. When water is needed it is pumped through pipes to homes and businesses in the community. Distribution tanks and pumping stations throughout the system provide storage of water and stable pressure to enhance reliability of water service and provide ample volume for fire protection.

The most common disinfectant or water treatment chemical is Chlorine. Other water treatment chemicals used less often are monochlorines and chlorine dioxide. Monochlorines are like the distance runner with a single shot rifle hunting bacteria, they dissipate at a slower rate than Chlorine, so the chlorine residuals are there for a long period.

But, they oxidize as a slow pace so they can only kill bacteria at a slow rate. Monochlorines can be overwhelmed if there is a disturbance like water main construction, water hammer or a fire flow event in the piping system that causes a release of a large dose of scale or biofilm containing a lot of legionella bacteria.

  1. Chlorine Dioxide is like the sprinter of the water treatment chemicals carrying an “uzi” machine gun to attack bacteria.
  2. The Chlorine Dioxide oxidizes rapidly and will run out of ammunition that is used to fight bacteria faster than Monochlorine and Chlorine.
  3. Chlorine Dioxide, however, will oxidize (deplete its ammunition) rapidly and be ineffective over long periods of time because it dissipates much faster than other water treatment chemicals.

Chlorine has been the most popular water treatment chemical over the years and it is like a middle distance runner of water treatment chemicals with an assault rifle. It is fast and very effective at killing bacteria and other contaminants. The things that affect the dissipation rate of all of these water treatment chemicals are the PH of the water, the number of contaminants present, the piping material, the temperature and time.

Chlorine dissipation rate Chlorine typically must be above 0.5 parts per million (ppm) of free chlorine in order to be effective against Legionella bacteria and other organisms in the water supply. You should try to maintain a minimum level of 1 ppm of free chlorine in all parts of the building water system in order to have a safety factor for killing bacteria in the water system.

When the water leaves the water treatment plant, the Chlorine levels are generally between 2 ppm and 4 ppm. The quality of the water, piping material, temperature and flow rate (which is a factor of time) all combine with the water treatment chemicals and cause it to react and oxidize as long as it can until it gets to the point it can no longer be effective at fighting bacteria.

This is referred to as the rate of dissipation. Prior to1992 water conservation efforts, the rate of dissipation from 4 ppm to 0.5 ppm could occur as quick as 1-½ days in galvanized piping systems. The rate of dissipation from 4 ppm to 0.5 ppm could take 10 to 12 days in PVC or lined cast iron piping systems.

For unlined cast iron piping systems, it takes about 4-½ days for the chlorine to dissipate from 4 ppm down to 0.5 parts per million. Given the recent water flow rate reductions and fact we must maintain the water mains sizes to accommodate periodic fire flow rates from fire hydrants, the amount of time that water is held in the water mains and distribution piping is exceeding the time required to maintain water treatment chemical levels that will be effective at fighting off contaminants like Legionella, Cryptosporidium, E.coli and many other organic contaminants.

Since 1992, shower flow rates have gone from 5 to 7 gallons per minute (gpm) down to 1.75 gpm to 2 gpm. Water closet flow rates have gone from 3.5 to 5 gallons per flush (gpf) down to 1.28 gpf to 1 gpf. Previously, water would take about three to four days to flow from the water treatment plant to the farthest outlet.

Now, on average it takes about 12 to 16 days. This is why many water utilities are switching to monochlorines, which are not as effective when there are large doses of scale and bacteria introduced to the piping system. Minimum disinfectant levels to effectively control Legionella bacteria Chlorine is the most common disinfectant used by municipal water departments for treatment and disinfection of domestic water distribution systems.

  • The water utilities have a goal to produce domestic water or drinking water that has a minimum residual disinfectant level between two to four parts per million for Chlorine or Monochlorine.
  • For Chlorine Dioxide, they will generally have a maximum of 800 parts per billion.
  • The minimum level of Chlorine Dioxide must be monitored because it dissipates faster than Chlorine and Monochlorine.

As the water flows through water distribution mains the Chlorine reacts with the contaminants in the water and the walls of the pipe and the heat in the environment and the Chlorine will dissipate as it reacts with these conditions. Chlorine will also dissipate as time passes when the water sits still, and faster as the temperature rises.

  1. The heat effect on the Chlorine dissipation rate is why hot water systems at temperatures below 124°F are more susceptible to bacteria growth than cold water systems.
  2. Disinfectant levels should be monitored at the ends of water distribution systems to assure disinfection levels are being maintained.
  3. If a facility is located in a remote portion of a water distribution system, it is possible that the disinfectant levels could be non-existent or below the minimums recommended to control bacteria and pathogens in the water system.

The increase in water conservation efforts and reduction in water flows has caused a decrease in disinfection chemicals in some remote water distribution systems. OSHA design recommendations The Occupational Safety and Health Administration (OSHA) gives advice on controlling Legionella in building water systems.

  • OSHA misquotes the type of mixing valves that should be used at delivery points.
  • Hey need to clarify the language to address “temperature limit stops” and “temperature limiting valves” instead of “pressure-independent, thermostatic valves.” The plumbing codes clearly outline what is acceptable for scald protection.

OSHA also states that point-of-use water heaters can eliminate stagnation of hot water in infrequently used lines. This claim is not scientifically based. There is no evidence that point-of-use or tankless water heaters perform any better than any other type of water heater with respect to controlling Legionella bacteria growth.

Actually, it is more likely that certain point-of-use water heaters do not raise the hot water temperature to a disinfecting temperature. I am aware of instantaneous/tankless water heaters that have tested positive for Legionella bacteria and other pathogens in several outbreaks that I have investigated.

These point-of-use water heaters only raise the hot water temperature to the usage temperature instead of to a higher disinfecting temperature. Some instantaneous steam water heater models raise the temperature to disinfecting temperatures and then use a mixing valve to blend the hot water temperature back down to a stable temperature for distribution.

Other types of heaters work in a similar way, but the most common heaters do not have excess capacity for disinfection temperatures. OSHA’s advice on controlling Legionella also implies that tanks can cause Legionnaires’ Disease. It should be noted that it is most commonly storage temperatures not tank size that allow legionella bacteria to grow.

There is no scientific evidence of tanks causing Legionella to grow when storage temperatures are maintained properly and tanks are recirculated and disinfected periodically if required. Domestic hot water should be stored at a minimum of 140°F and delivered above the maximum temperature at which legionella grows and multiplies.

ASHRAE Guideline 12 has recommended a couple of degrees safety factor and a minimum hot water distribution temperature of 124°F to all fixtures. Hot water temperatures to all other fixtures will be higher and it can be mixed down to a safe temperature using the proper code-compliant, tempering valve to limit the hot water temperature coming from the fixture outlets for scald protection.

OSHA recommends the hot-water tank be drained periodically to remove scale and sediment, and flushed and cleaned with a chlorine solution, if possible. Many water heater manufacturers recommend a mild acid solution be circulated through the heater to de-lime the heater as required in the maintenance instructions.

  1. The tank must be thoroughly rinsed to remove excess acid and chlorine before reuse.
  2. OSHA recommends eliminating dead legs when possible, or installing heat tracing to maintain 122°F in the lines.
  3. I disagree with heat tracing in general because it allows stagnant water.
  4. The better solution would be to use a circulated hot water systems with the entire loop kept above 124°F.

OSHA recommends removing rubber or silicone gaskets which provide a surface for biofilm and nutrients for the Legionella bacteria. Again, I disagree. If the water is maintained with the proper water treatment chemical levels and/or at the proper temperatures to prohibit growth, legionella will not be a problem with gasket materials.

  • OSHA recommends frequent flushing of these lines to reduce growth.
  • I fully agree here and would like to see automatic flushing systems for schools, sporting facilities, seasonal resorts and other building types where the building could sit unoccupied for long periods of time.
  • I also believe domestic hot-water recirculation pumps should run continuously and they should be excluded from energy conservation measures that shut them off in off peak hours.
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OSHA recommends raising the water-heater temperature to control Legionella bacteria growth. They also recommend periodically raising the hot water temperature to pasteurize the hot water system by raising the water-heater temperature to a minimum of 158°F for 24 hours and then flushing each outlet for 20 minutes.

It is important to flush all taps with the hot water because stagnant areas can “re-seed” the system. Exercise caution to avoid serious burns from the high water temperatures used in the heat-and-flush or Pasteurization process. This heat and flush method of Legionella control should be done under controlled conditions to prevent scalding.

OSHA recommends periodic chlorination of the system storage tanks to produce 10 ppm free residual chlorine and flushing of all taps until a distinct odor of chlorine is evident is another means of control. Chlorine monitors and In-line chlorinators can be installed on the building water service lines.

  • It should be noted that chlorine is quite corrosive and can shorten the service life of plumbing components if the chlorine levels are too high.
  • Control of the pH is extremely important to ensure that there is adequate residual chlorine in the system.
  • Alternative means to control Legionella growth include the use of metal ions such as copper or silver (which have a biocidal effect) in solution.

Ozonization injects ozone into the water. Ultraviolet (UV) radiation also kills microorganisms. Commercial, in-line UV systems are effective and can be installed on incoming water lines or on recirculating systems, but stagnant zones may diminish the effectiveness of this treatment.

  1. Scale buildup on the UV lamp surface can rapidly reduce light intensity and requires frequent maintenance to ensure effective operation.
  2. OSHA recommends domestic cold water systems maintaining cold-water lines below 20 degrees 68°F to limit the potential for amplification of the bacteria.
  3. Elevated levels of Legionella have been measured in ice machines in in many building types including hospitals.

Ice machines are often implicated in Legionnaires Disease outbreaks because the cold-water lines supplying the ice machines are typically long flexible copper pipe coiled behind the ice machine to allow for the ice machine to be removed for cleaning and maintenance.

  • ASHRAE 188 Standard As you may have heard ASHRAE has recently published the ASHRAE 188 Legionellosis: Risk control for building water systems.
  • At the recent ICC Hearings, I proposed adoption of the ASHRAE standard for the design and installation of building water systems in the plumbing and mechanical codes.

Not surprisingly, the standard was turned down for adoption because there were many people that did not know what is in the new standard and there was the fear of the unknown. It will be proposed again in future code cycles and by then everyone should have a better understanding of what the standard covers.

  • Until then it is still the industry standard for the control of Legionellosis associated with building water systems.
  • As water and energy conservation efforts continue to reduce water flows and redirect water for reuse and reclaimed water systems we will undoubtedly see an increase in contamination of our potable water/drinking water supplies.

We need to be aware of the delicate balance between reduced water flows and increased bacteria growth from stagnant water and reclaimed or reuse water systems. Ron George, CPD, is president of Plumb-Tech Design & Consulting Services LLC. He can be reached at: office 734-322-0225; cell phone 755-1908; and website www.Plumb-TechLLC.com,

How long after exposure to Legionella do symptoms appear?

Legionnaires’ Disease – Legionnaires’ disease is very similar to other types of pneumonia (lung infection), with symptoms that include: Legionnaires’ disease symptoms are similar to other types of pneumonia and it often looks the same on a chest x-ray.

Cough Shortness of breath Fever Muscle aches Headaches

Legionnaires’ disease can also be associated with other symptoms such as diarrhea, nausea, and confusion. Symptoms usually begin 2 to 14 days after being exposed to the bacteria, but it can take longer. If you develop pneumonia symptoms, see a doctor right away.

Can Legionella survive in chlorinated water?

Thus, Legionella are able to survive in habitats with a greater temperature range, are more resistant to water treatment with chlorine, biocides and other disinfectants, and survive in dry conditions if encapsulated in cysts.

Do water filters prevent Legionella?

Over 20 years ago we introduced the first disposable Point-of-Use (POU) water filter to the market, providing a unique solution for the removal of waterborne pathogens from the drinking water distribution system. This unprecedented innovation brought an ease of use that revolutionized hospital hygiene and water management for healthcare, public & residential facilities.

How common is Legionella in water systems?

Legionnaires’ disease is a very small percentage of all waterborne illness. – According to the CDC, about 8,000 cases of Legionnaires’ disease are now reported each year in the United States. In general, the number of cases reported to the CDC has been on the rise over the past decade.

Does water with Legionella smell?

Can you smell Legionella? – Yes, it’s possible to Smell legionella. Your water may have a distinct “rotten egg” or sulfur smell when it’s contaminated.

What do you do if you test positive for Legionella?

Expert assistance following positive legionella testing – Since positive legionella testing results can be extremely worrying for anyone in charge of a business or other property, it can be reassuring to call in the experts, such as Legionella Control International.

Get expert assistance if you are concerned about your legionella results

While the person in charge of water system safety, referred to as the Responsible Person retains responsibility for dealing with the situation, it can still be sensible to resort to someone qualified and experienced in these situations. They can review the test results and any other data available including the legionella risk assessment.

What does positive Legionella test mean?

Urinary Antigen Test – The most commonly used laboratory test for diagnosis of Legionnaires’ disease is the urinary antigen test (UAT), which detects a molecule of the Legionella bacterium in urine. If the patient has pneumonia and the test is positive, then you should consider the patient to have Legionnaires’ disease.

The test can remain positive for a few weeks after infection, even with antibiotic treatment. The UAT detects the most common cause of Legionnaires’ disease, L. pneumophila serogroup 1. However, all species and serogroups of Legionella are potentially pathogenic, so a patient with a negative urinary antigen result could have Legionnaires’ disease caused by other Legionella species or serogroups, which is why using culture and UAT in combination is recommended.

Sensitivity varies depending on the quality and timing of clinical specimen collection, as well as technical skill of the laboratory worker performing the test. The table below provides general ranges for the sensitivity and specificity of each diagnostic test.

Table provides general ranges for the sensitivity and specificity of each diagnostic test

Test Sensitivity (%) Specificity (%)
Culture 20–80 100
Urinary antigen for L. pneumophila serogroup (Lp1) 70–100 95–100
Polymerase Chain Reaction (PCR) 95–99 >99
Direct Fluorescent Antibody (DFA) Stain 25–75 >95
Paired serology 80–90 >99

1 Cross reactions with other species and serogroups have been documented.2 Avni T, Bieber A, Green H, et al. J Clin Micro,2016;54(2):401–11.3 CDC labs do not perform serologic testing for legionellosis diagnosis due to inherent challenges in obtaining appropriate specimens.

How long does water have to sit for Legionnaires?

Bacteria when in ideal conditions will grow, if you put legionella on an agar plate and incubate it for 7 – 10 days with a temperature range of between 20˚C and 50˚C, a colony will form of millions of bacteria that you will be able to see.

How long does it take to get Legionella after exposure?

Legionnaires’ Disease – Legionnaires’ disease is very similar to other types of pneumonia (lung infection), with symptoms that include: Legionnaires’ disease symptoms are similar to other types of pneumonia and it often looks the same on a chest x-ray.

Cough Shortness of breath Fever Muscle aches Headaches

Legionnaires’ disease can also be associated with other symptoms such as diarrhea, nausea, and confusion. Symptoms usually begin 2 to 14 days after being exposed to the bacteria, but it can take longer. If you develop pneumonia symptoms, see a doctor right away.