Legionella and the home shower in Ohio

Legionella bacteria can grow in household plumbing and reach people through the mist of a shower. This page sets out what the Centers for Disease Control and Prevention says about how that happens and what to do at home, its advice on the water heater, how common the disease is in Ohio and the seven Central Ohio counties, and where Ohio's rules apply, quoted from the agencies.

Last updated September 2026 · From the Centers for Disease Control and Prevention, the Ohio Department of Health and the Ohio Administrative Code, each read September 25, 2026 · No prices on this page; the Estimate Builder carries those · Part of the knowledge base

What it is, and how a shower comes into it

The Centers for Disease Control and Prevention describes Legionnaires' disease as a serious pneumonia caused by Legionella bacteria, which live in water and, in the CDC's list of what helps them grow, favor the slime that forms inside pipes and fixtures, temperatures from 77 to 113 degrees Fahrenheit, water that sits still and low disinfectant. People get sick by breathing in small droplets of water that carry the bacteria; the CDC lists showerheads and sink faucets first among the places that make that mist, and says the disease generally does not spread from person to person. It also says most healthy people exposed to Legionella do not get sick. Those at increased risk, in its list, are people 50 or older, current or former smokers, and people with chronic lung disease, cancer, diabetes, kidney or liver failure, or a weakened immune system.

What the CDC says to do at home

The CDC's advice for a home turns on water that has sat unused, like a week or longer. Its steps for a faucet or shower nobody has used in a while: turn on the cold water fully and let it run for 2 minutes, turn it off, then turn on the hot water fully and run it until it starts to feel hot. It says to flush every faucet and shower after a drop in water pressure, to clean showerheads and faucet aerators whenever buildup shows, which may mean soaking them in a solution such as white vinegar, and to maintain or replace showerhead and faucet filters, because germs can grow in filters too. It adds that many water heater makers recommend flushing the heater every year, before moving into a home, after plumbing work and when tap water is discolored.

On the water heater's setting, the CDC's own sentence is that keeping a home water heater between 130 and 140 degrees Fahrenheit can kill germs like Legionella but also raises the risk of burns, and that a heater set above 120 degrees should be paired with thermostatic valves that mix hot and cold at the tap. The CDC says this is especially important if young children, older adults or others at increased risk of burns live in the home. It tells readers to ask a healthcare provider whether setting the heater to 130 or above is right for them. The Consumer Product Safety Commission's 120-degree advice is on the page on hot water for a Central Ohio shower, and what Ohio's plumbing code asks of a shower valve, including its 120-degree limit, is on the page on Ohio's plumbing code; this page does not choose a setting.

How common it is in Ohio

Reported cases of Legionnaires' disease have been increasing since the early 2000s, the CDC says, and Ohio's reported rate has run higher than the nation's in every year of the CDC's recent series, between about 1.9 and 2.9 times the national rate from 2014 to 2025. The CDC says rates are highest among older adults, in the Northeast and Midwest, and in summer and fall. These are reported cases per 100,000 people; the 2024 and 2025 figures are provisional. The CDC has also said the disease might be underdiagnosed, so reported counts are a floor.

The Ohio Department of Health's infectious disease summary counts legionellosis, which includes Legionnaires' disease and the milder Pontiac fever, by county. From 2016 to 2025 Ohio recorded 6,626 cases; the seven Central Ohio counties together recorded 1,440 of them, about 22 percent, most in Franklin County, the state's second highest after Cuyahoga. The smaller counties' counts are given here only as multi-year totals.

Where Ohio's rules apply

Ohio's rules require water management programs, run according to CDC guidance, to manage the risk of Legionella in building water systems at hospitals and residential care facilities, both since 2024, and at nursing homes, effective July 17, 2025. No Ohio rule for a single-family house was found. How much of a home's energy goes to heating water, and what heats it, is on the page on hot water and home energy.

Scope, plainly. This page quotes the CDC and the Ohio Department of Health. It is not medical advice; symptoms, testing and treatment are questions for a healthcare provider, and the CDC says Legionnaires' disease is treatable with antibiotics.

Sources

Every figure, date and quotation on this page comes from one of these documents, read on the date given. Where two of them disagree, the page says so.

• Centers for Disease Control and Prevention, Preventing Waterborne Germs at Home, March 15, 2024; read September 25, 2026.
• Centers for Disease Control and Prevention, How Legionella Spreads, June 9, 2025, and About Legionnaires' Disease, August 6, 2025; read September 25, 2026.
• Centers for Disease Control and Prevention, Legionellosis Surveillance and Trends, July 8, 2026, incidence by year and by state, and Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires' Disease — North America, 2000–2014, Morbidity and Mortality Weekly Report 65(22), June 10, 2016; read September 25, 2026.
• Ohio Department of Health, Summary of Infectious Diseases in Ohio, legionellosis by county and year, last refreshed September 24, 2026; read September 25, 2026.
• Ohio Administrative Code, rules 3701-22-07 (hospitals), 3701-16-12 (residential care facilities) and 3701-17-11 (nursing homes, effective July 17, 2025); read September 25, 2026.

Common questions