Can a Water Heater Cause Carbon Monoxide Poisoning?

The invisible killer is in your house! Can you imagine more horrible words that warn about the danger coming from the water heater? We are talking about carbon monoxide – a gas that occurs during the water heating process in some types of gas-powered boilers and water heaters.

See what styles of hot water heaters are potentially dangerous, how to recognize the hazard, stop the leak and protect yourself from poisoning?

In this article:

  1. What is carbon monoxide (CO)?
  2. Why is CO dangerous for your health?
  3. Prevention and how to detect carbon monoxide leaking
  4. How to choose a carbon monoxide detector?
  5. FAQ

Carbon Monoxide as the Product of Incomplete Combustion

First, let’s take a look at what carbon monoxide gas is, and then we’ll see how to check for carbon monoxide leaks in a water heater.

Living organisms consist largely of carbon or hydrocarbon compounds, which is why fossil fuels such as coal, oil, natural gas, and wood also contain these components. The burning process breaks down the hydrocarbons that have been stored for millions of years, and optimal combustion releases carbon dioxide (CO2) as a byproduct.

However, in the case of gas water heaters, incorrect combustion caused by a defect or insufficient oxygen can produce carbon monoxide (CO) as the burning product.

Given the above, it is clear that every combustion process (i.e., fuel-burning appliance) inside the home or office may pose a risk. Gas water heaters and oil and gas boilers are among the sources of danger.

As for electric water heaters, they do not leak carbon monoxide, so there is no need to worry about carbon monoxide poisoning in such cases.

Why Is CO Dangerous for Your Health?

Carbon monoxide is an odorless and colorless gas that can have serious consequences, including death, due to its aggressive and invisible attack on the human body.

In the bloodstream, carbon monoxide binds to hemoglobin in the place reserved for oxygen, which results in less oxygen getting into the cells (hypoxia). Additionally, the carbon dioxide (CO2) produced by the body as a byproduct of energy production can no longer be transported to the lungs via the blood and exhaled from the body. The result of these two processes is suffocation.

Even small amounts of carbon monoxide in the blood can contaminate the body if the source is not found and eliminated in time. A concentration of CO in the blood leads to a lack of oxygen and can cause damage to all body cells, including the brain, nerves, and other organs.

Signs of Carbon Monoxide Poisoning

The first signs of CO poisoning include headache, dizziness, difficulty concentrating, fatigue, nausea, and vomiting. If left untreated, unconsciousness may follow, ultimately leading to the person stopping breathing and death.

Certain groups of people are more vulnerable than others, including small children, the elderly, and those with chronic heart disease, anemia, and breathing problems.

Prevention and How to Detect Carbon Monoxide Leaking in Time

To determine the current concentration of carbon monoxide in the air, it is recommended to purchase and install CO detectors in areas where they are needed, such as the bedroom and living room. There are various devices available on the market, so it’s important to choose one that meets your needs and budget.

It’s also important to consult a professional plumber, as unclean combustion caused by defects or insufficient oxygen can result in a water heater emitting carbon monoxide. Negative pressure in the installation room can also lead to carbon monoxide poisoning. If at least one exhaust system and a fireplace are operating simultaneously, exhaust gases can be pushed into the room instead of flowing out of the chimney.

To prevent these issues, ask a plumber to inspect your water heater and/or the entire system and propose measures. Clogged exhaust ducts, a clogged chimney, or a defective exhaust pipe can lead to poor combustion, so it’s important to address these issues promptly.

How to Choose a Carbon Monoxide Detector

The simplest carbon monoxide detector costs 20-25 dollars, and it is designed to plug it into the electrical outlet. A slightly more expensive model is equipped with a battery-powered backup option.

The next types are the units that combine a smoke detector and carbon monoxide detector. They are always hard-wired and positioned on the ceiling because the smoke detector requires high mounting.

Digital carbon monoxide detectors look nice; they usually have a display that shows CO levels continuously. The freestanding device may be put on the bookshelf, for example. The price is affordable – 40-55 dollars.

How many CO detectors do you need?

Experts recommend one on every floor or one within 10 feet of each bedroom door.

Be aware that a detector has a limited shelf life. The advice is to replace it every five years. Check the manufacturing date when you buy one – it can be expired.


While water heaters provide a common and convenient source of hot water in many homes, they can also pose a potential danger if not properly maintained and operated.

Carbon monoxide leaks from water heaters and other gas appliances can lead to serious health problems or even death if left undetected.

To ensure your safety, it is crucial to have your gas device regularly inspected by a licensed professional, install carbon monoxide detectors, ensure adequate ventilation in the area, perform regular maintenance, and educate everyone in the household about safe practices if a high level of CO is detected.


How Do I Know If My Water Heater Is Giving Off Carbon Monoxide?

Carbon monoxide is an odorless gas that cannot be detected by senses. Signs of carbon monoxide release from a gas water heater include blackening or soot around the heater, pilot light frequently going out, and symptoms such as headache, nausea, dizziness, weakness, confusion, or chest pain in those near the gas unit.

Note that it is not recommended to rely on any method other than a carbon monoxide detector to detect the presence of carbon monoxide in a home.

How Often Should I Have My Water Heater Inspected for Carbon Monoxide Leaks?

It is recommended to have your water heater inspected for carbon monoxide leaks at least once a year by a licensed professional. Regular maintenance and inspection can help prevent carbon monoxide leaks and ensure that your water heater is operating safely and efficiently. During the inspection, the technician will check the combustion chamber, flue pipe, and ventilation system for any damage, corrosion, or blockages that could cause carbon monoxide to leak into your home. They will also check for proper airflow and combustion, and make any necessary repairs or adjustments to keep your water heater running safely.

How Long Does It Take for Carbon Monoxide Poisoning to Take Effect?

Carbon monoxide poisoning can cause mild symptoms like headache and nausea within hours of exposure to low concentrations of gas, or more severe symptoms like loss of consciousness within minutes to hours of exposure to high concentrations. Prolonged exposure to low levels of carbon monoxide can lead to chronic health problems like memory loss and heart disease. Seek immediate medical attention if you suspect carbon monoxide poisoning.

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