Legionnaires’ Disease From Shower Water: How the Spray Route Works

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This post covers legionnaires disease from shower water, using the EPA and DC Health pages. Legionnaires’ disease from shower water is a real route in the sources, but it is a route through spray, not through a drink. The EPA says “Legionella exposures primarily occur when a person breathes in spray or small droplets that contain the bacteria.” It also says that a much less common route can occur when water droplets get into the lungs accidentally while swallowing. The DC Health handout describes the same exposure: people can be exposed when they breathe in small droplets of water in the air that contain Legionella. This post explains what that means for a shower and what the sources leave open.

Quick answer

• Legionnaires’ disease is a serious type of pneumonia caused by Legionella. The EPA says the milder form, Pontiac fever, is a flu-like illness.
• The main exposure is breathing in spray or small droplets. A shower makes that kind of spray, so it can be part of the route.
• Most healthy people exposed to Legionella do not get sick, according to the EPA. Some groups face higher risk.
• The sources do not give the chance of infection from a single shower, and they do not confirm any particular case.

What the disease is

The EPA says Legionella bacteria “can cause Legionnaires’ disease, a serious type of pneumonia (lung infection), or a milder influenza-like illness known as Pontiac fever.” The DC handout uses the umbrella term legionellosis for both forms. The EPA also notes that the disease was named after an outbreak at a convention in 1976, and that Pontiac fever was linked to Legionella after it was first identified in 1968.

The EPA adds a warning about severity. It says that “About 1 in 10 people who get sick with Legionnaires’ disease die from the illness.” It also says the disease is likely underdiagnosed because its symptoms may resemble other lung infections. Those are statements from the EPA page, and they are the basis for the disease part of this post. This post does not give symptoms or treatment, and the sources do not replace a doctor’s advice.

How shower water becomes a spray risk

The EPA is direct about the fixture role. It says that “Showerheads, sink faucets, and humidifiers can create spray, or small droplets, that can release bacteria into the air.” A shower is a spray device by design. If the water and the head hold Legionella, the spray is the mechanism the EPA describes.

The DC handout puts the same point in plain words: “You can be exposed to legionella bacteria if you breathe in small droplets of water in the air that contain legionella.” The handout does not describe how large a shower’s spray is, and it does not compare head designs.

Who faces higher risk

The EPA lists people who may be more susceptible to Legionella illness. They include people 50 years or older, current or former smokers, people with weakened immune systems or who are immunocompromised, people with chronic lung disease, people with cancer, and people with underlying illnesses such as diabetes, kidney failure or liver failure. The EPA says most healthy people exposed to Legionella do not get sick.

The EPA also says that if you are unsure whether to take prevention steps, a healthcare provider or public health professional in your area can advise you. The sources do not tell readers how to judge their own risk beyond that list. If you are in one of the listed groups, speak with a clinician.

Reducing spray at home

The EPA lists steps that reduce spray from a shower. They are the steps most readers can act on:

• Clean the showerhead and hose when you see mineral buildup or a slimy film, and follow the manufacturer’s cleaning method.
• Open a window or use an exhaust fan when you shower, so spray leaves the room.
• Keep the water heater and plumbing temperatures in the ranges the sources describe. The EPA gives 124 degrees Fahrenheit as a level above which growth is limited, and 80 degrees Fahrenheit as a level below which growth is limited, while growth is best between 80 and 120 degrees.
• Flush outlets that have not been used. The DC handout says to run or flush faucets and showerheads for at least 2 minutes if they have been out of use for more than a week.

The EPA says high-risk individuals may also consider point-of-use filters for sinks and showerheads. It adds that those devices must be maintained and replaced on schedule, and that the manufacturer’s instructions apply.

Water temperature and scald risk

The EPA says that “Setting the thermostat at or above 140⁰F can often keep temperatures high enough (above 124⁰F) throughout the plumbing system to prevent Legionella growth.” It also says hot water at the faucet or shower “may present a scalding risk at temperatures above 117⁰F.” The page recommends thermostatic mixing valves close to outlets if you raise the setting, and it says to check state or local codes first.

The DC handout says to set water heaters to a minimum of 120 degrees Fahrenheit and to consider 130 to 140 degrees Fahrenheit. The two sources give different ranges, so read the local rules and the heater manual before you adjust a setting.

Outbreaks and the shower question

The EPA says outbreaks of Legionnaires’ disease “are often associated with buildings or structures that have complex water systems, such as long-term care facilities, hospitals, cruise ships, hotels, and resorts.” It adds that “The most likely sources of infection include water used for showering, hot tubs, decorative fountains, and cooling towers.” That places showers among the sources the EPA names, but the page is about large buildings, and it does not give a count of home cases linked to a shower.

The EPA also cites CDC analysis of outbreak reports. It says CDC “found that nearly all were caused by problems preventable with more effective water management”. The EPA’s own figures are broader. It says that “In 2021 Legionella was the cause of 50 % of waterborne disease outbreaks and 60% of deaths during those outbreaks.” Those figures describe outbreaks in general, not home showers, so they should not be read as a home risk rate.

The DC handout points readers in a similar direction for multiunit buildings. It says that if you live in a building with multiple units, you should check with the building owner or manager about a Water Management Program. A renter or condo owner may not control the building’s water system, and that is a reason to ask the building manager rather than to change only your own fixture.

For readers who also compare shower heads for flow and pressure, see our high pressure and water-saving shower head guide and the water-efficient hand-held shower head roundup. Those comparisons do not cover Legionella, and neither do the sources in this post.

Mistakes to avoid

• Treating Legionnaires’ disease as a drinking-water problem only. The EPA identifies spray as the main exposure route.
• Turning up the heater without a scald plan. The EPA gives a scald warning above 117 degrees Fahrenheit.
• Ignoring a shower that has not been used for a while. The sources treat stagnant water as a growth concern.
• Assuming a single shower confirms or rules out infection. The sources do not do that, and a clinician is the right person to ask.

Frequently asked questions

Can I get Legionnaires’ disease from drinking shower water?

The EPA says a much less common route can occur when droplets get into the lungs by accident while swallowing. Its main concern is breathing in spray.

Does everyone who breathes this spray get sick?

No. Most healthy people exposed do not get sick, according to the EPA, and some groups are more susceptible.

How common is it?

The EPA says health departments reported nearly 9,000 cases of Legionnaires’ disease in the United States in 2019, and that the true number is believed to be much higher. The EPA does not connect those cases to showers in a way this post can measure.

Should I see a doctor after a shower?

The sources do not give symptom guidance for this post. If you have symptoms of pneumonia or Pontiac fever and worry about exposure, contact a clinician.

How we chose these sources

We used the EPA page “Legionella in the Indoor Environment” as the federal source on spray and disease. We used the DC Health handout “Preventing Legionellosis at Home” (2025) as a local government handout for the home steps. The CDC prevention page returned a 404 error and the CDC site returned 403 errors to our fetch tool, so no CDC text is quoted. Search results from county and state handouts were not used as sources.

What we could not verify

• The chance of infection from one shower, or from a shower over time. The sources do not measure it.
• The symptoms and treatment of Legionnaires’ disease. This post does not cover them, and the CDC clinical pages were not available to us.
• Whether a given showerhead produces more or less spray than another. The sources do not compare models.
• Any link between a specific home shower and a specific case.

Sources

• US EPA, “Legionella in the Indoor Environment”, https://www.epa.gov/node/271246 (opened 2026-10-29). Saved text: research/sources-20261029/B4/legionnaires-disease-from-shower-water–epa-indoor-environment.txt
• DC Health, “Preventing Legionellosis at Home” (2025), https://dchealth.dc.gov/sites/default/files/dc/sites/doh/Preventing%20Legionellosis%20at%20Home_2025.pdf (opened 2026-10-29). Saved text: research/sources-20261029/B4/legionnaires-disease-from-shower-water–dc-health-home-handout.txt