Brown Stuff In Your Humidifier – What Is It And How To Remove It

Humidifiers are great to relieve the symptoms of dry air and the damage caused by central heating or cooling, but sometimes there’s brown sediment in their water tanks.

Brown sediment or residue in a humidifier is caused by minerals, mold, and dirt that accumulate inside the unit, and can be released into the air as brown particles. Mold, such as Cladosporium, Ulocladium and Taeoniella, easily grow in humidifiers.

The World Health Organization found people in buildings with humidifiers are more likely to be sick than people who live and work in buildings without them, precisely because they do not clean humidifiers often enough. This guide explains what this brown stuff is that can accumulate inside and around your humidifier, and includes easy to follow steps on how to clean and prevent it.

Why Your Humidifier (And Water) is Brown

The brown stuff in a humidifier falls into three groups: minerals, mold, and dirt.

The minerals naturally found in water, the mold that grows in the moisture, and dirt in the air form a progressively thick layer of sediment on the inside of the humidifier. This brown layer then leaches into the water, and from there into the air as tiny particles.

Here’s more information about each of these problems, followed by a step-by-step guide on how to remove the brown stuff from your humidifier:

Mineral Deposits

When your humidifier empties the water tank or you drain the water out, the minerals that are present in the water can stick to the insides of the unit.

These minerals are often calcium, sodium and magnesium.

This type of mineral dust is more likely to be white than brown, since calcium and sodium are light-colored and two of the most common minerals and water. But many minerals like iron, aluminium and boron are brown.

White mineral deposits can also turn brown as they mix with mold growths or tiny dirt particles in the water.

It’s important to remove any mineral deposits from humidifiers as they can be dispersed into our air by the humidifier, which is bad for our air quality.

Researchers have found a direct relationship between the mineral content of water and the number of particles released into the air by the humidifiers that use it. In fact, one study found that even low-mineral tap water causes humidifiers to send out air above international recommended air-quality standards.

Mold Growths

Bacteria and fungi (especially mold) grow very well in moist, warm environments – like a humidifier. Because they multiply extremely fast when left alone, they can form a furry brown layer inside your unit.

This also means mold particles and spores can be spread through your home in the air by the humidifier.

In one study, researchers found mold particles in more than half of all the humidifiers they tested, which shows that it’s an extremely common problem.

The most common fungi or mold in humidifiers are Cladosporium, Penicillium, and Aspergillus.

Cladosporium is the most common brown mold to see, while penicillium and aspergillus are more likely to be greenish or black.

Dirt Build-up

Humidifier’s are obviously not air tight, in fact they are constantly drawing air in. Unfortunately, air also has lots of tiny particles of dust and dirt in it that also enter the humidifier.

The particles of dust and dirt, and even pet hair and skin cells can build-up in the humidifier if it isn’t cleaned regularly. These can develop into brown deposits by themselves, or mix with mineral deposits to form a hardened crust.

If the water you use is also high in sediment, known as TSS (total suspended solids) this build-up can happen quickly. If possible, always use distilled or deionized water in your humidifier and avoid using tap water or well water.

How To Remove The Brown Stuff In Your Humidifier

Most of us know what mold looks like. It’s either irregularly-shaped specs of white, black, green, yellow, orange, or brown, or it looks like a furry growth. Mold is usually soft enough that it will start coming off when you scrub it, although that’s not the best way to clean it.

On the other hand, the sediment caused by minerals can become so hard that scrubbing seems to make no difference. When the humidifier is dry, mineral sediment also feels dry to the touch, while some molds are slimy even when dry.

It doesn’t matter hugely which problem you have, as the solution is the same for all three and involves two steps:

1. Descale
2. Disinfect

1. Descale

If you still have your user manual, you’ll find specific steps on how to descale your particular model of humidifier. However, these general steps should be fine to use on all humidifiers:

• The most common minerals are alkaline, which means that an acidic substance like white vinegar can help you dislodge them. This will also help if your humidifier is releasing a white dust.
• Spray the vinegar inside the tank and tray and scrub hard with a wet scrubber or brush. Alternatively, you can make a solution with equal amounts of vinegar and water and dip the brush in it frequently.
• If the mineral scale is particularly stubborn, pour one of the vinegar and water solution straight into the tank and tray and let it stand for 20 minutes before you resume your brushing.
• If the white vinegar seems ineffective, your humdifier might be contaminated with acidic minerals, in which case a solution of baking soda and water can work.
• Stir four tablespoons of baking soda into a quart of warm water, dip your brush or scrubber, and scrub the tank and tray.
• If you have an evaporative humidifier, place the filter or wick into clean, chemical-free, cold water and swish it around for 10-20 minutes to dislodge the minerals. If they don’t come off, it’s time to replace the filter. Do not use chemicals, as these can destroy the filter’s antimicrobial coating.
• These cleaning methods will also remove any dirt or dust that’s stuck in the device.

2. Disinfect

If your appliance’s manufacturer has specific guidelines, follow those. Otherwise, the following suggestions are safe and effective:

• Add one tablespoon of unscented (Regular Scent) chlorine liquid bleach to one gallon of water and let it stand in the tank for 20 minutes before scrubbing with a brush.
• Rinse the tank thoroughly (at least two or three times) and dry it before the next use.
• If you have a portable humidifier, you can take the it outside, to put the bleach solution in the tank, and to run it for 30 minutes where no one is in danger of inhaling strong chemicals. Then rinse it well before using it again.

Remember that evaporative humidifiers are likely to have antimicrobial coating on the filter. Disinfectants might destroy this coating, so don’t expose it to one of these. Instead just replace the whole filter if it looks like mold is growing on it. Never use a filter that has mold growing on it.

• To prevent yourself from breathing mold spores while cleaning, it’s best to wear an N-95 face mask while scrubbing.

How To Prevent A Dirty Humidifier

The best way to prevent a dirty humidifier, and stop brown, black or pink stuff growing in it, is by cleaning it regularly and using purified water:

• Empty the tank, dry all surfaces thoroughly, and refill it with clean water every one or two days.
• On days when you don’t use the unit, empty it of water and allow the tank and filter to dry.
• Pour distilled water rather than tap water in the tank. Distiled water doesn’t contain minerals, sediment, bacteria, or fungi to clog up your humidifier. Water that has gone through your own reverse osmosis system is also clean enough, and purified bottled water to which no minerals/electrolytes have been added are fine too.
• Take the unit apart once a week and wipe all the pieces with a clean, dripping-wet cloth, excluding those containing electronic or electric components. This allows you to catch potential problems before they develop.
• Make sure that the humidifier is clean and dry before you store it at the end of the season, and clean it again at the beginning of the new season before use.
• Replace the filter of your evaporative humidifier according to your manufacturer’s recommendations. Sometimes this is surprisingly frequent, even as often as every 2 weeks.
• Since research shows that ultrasonic and impeller humidifiers release a lot more particles than evaporative and steam humidifiers do, you may want to add a bacteriostatic treatment, such as Essick Air and a general mineral/dirt cleaner like Protec Humidifier Tank Cleaner to the tank when you fill up your ultrasonic or impeller device.

Humidifier’s Impact On Our Health

Over the years, researchers have linked several health conditions to the presence of minerals, molds, and dirt in the air, including allergies, persistent cough, asthma, pulmonary fibrosis, diminished lung function, and cancer.

• Asthma is 70 % more common in kids who use humidifiers, with researchers suspecting dirty humidifiers and excessive humidity to be responsible. Incredibly, it is a larger asthma risk than even environmental tobacco smoke.
• Molds like Cladosporium cause persistent respiratory allergies.
• When tiny particles of minerals and chemicals settle inside the lungs, they can cause asthma, inflammation, diminished lung function, and cancer.
• Mold causes wheeze and persistent cough, especially in children and infants.
• An influenza -like illness called humidifier fever with symptoms like fatigue and headache has been linked with the use of moldy humidifiers.
• Molds like Penicillium can cause hypersensitivity pneumonitis, a form of allergy that leads to shortness of breath, coughing, exhaustion, weight loss, and ultimately pulmonary fibrosis.
• Molds like Penicillium and Aspergillus can also cause Persistent alveolitis, a condition that involves dry coughing, wheezing, body chills and sweats, fatigue, and later permanent changes in lung tissue that compromise lung function.
• Chemicals produced by fungi in the air can weaken your immune system and put you at risk of bacterial and viral infections.
• If they end up in your food, chemicals produced by fungi can cause nausea, vomiting, diarrhea, abdominal pain, esophageal pain, laryngitis, asphyxiation, gastroenteritis, and cancer.

By keeping your humidifier clean, and using distilled water you can get the most out of your appliance and enjoy perfectly humid air all year round without the health risks.