Those Brown Streaks on the Bathroom Wall Are Gross. So Where Do They Come From? (2024)

The terms “brown streaks” and “bathroom” are two no homeowner wants to hear joined together.

Those brown streaks on your bathroom walls, ceiling, or door frame—which some say resemble droplets of maple syrup—are vexing and unsightly. Once you notice them dirtying up the surfaces of your bathroom, they’re tough to ignore. So where do they come from?

In the interest of science (and peace of mind), we set out to investigate this alarming phenomenon.

Possibility No. 1: Paint surfactant

The average shower lasts about 8 minutes, according to the Environmental Protection Agency, and can reach 112 degrees Fahrenheit. All of that steam does a number on your paint and, more specifically, one of the ingredients in the paint: surfactant.

“Surfactant is an ingredient in latex paint that is often used to add stability to the paint,” says Stephen Keighery, a cleaning expert and founder of Home Buyer Louisiana. Many of the old homes his team has purchased have had the issue of brown streaks in the bathroom.

“The brown beads are most likely the result of surfactant leaching. The moisture and steam from showering can cause it to separate from the paint mixture and diffuse into the paint’s surface, causing dark spots and droplets.”

Possibility No. 2: Smoke

Cigarettes have been linked to countless health problems, but they might also be causing those ugly blotches in your bathroom.

“Over time that smoke in the air can accumulate, and when there’s moisture in the air from showering, it can turn into brown droplets,” says Melanie Hartman, owner of Creo Home Buyers in Maryland.

Hartman also points out that smoke and steam from cooking can come together to create brown droplets on the wall, especially if you live in a studio apartment or an open floor plan where smoke or steam can travel.

Possibility No. 3: Mold

Excess steam and insufficient ventilation can also cause brown marks in the bathroom in the form of mildew and mold.

Gene Fitzgerald of Best Osmosis Systems in San Diego says mildew and mold can be caused by the condensation that builds up from excess steam and insufficient ventilation.

“The drip marks from hot water often result in brown lines running down your wall when the water evaporates, leaving mineral deposits that resemble droplets,” Fitzgerald explains. “They can spread into bigger spots if left unattended.”

Possibility No. 4: Damaged pipes

An under-the-radar (and admittedly rare) cause of these brown spots can be broken pipes.

“Damaged or broken pipes in a home’s walls can lead to serious headaches when they’re not detected early,” says Raj Midha, general manager and a cleaning expert at American Home Shield in Memphis, TN. “Signs include discolored spots on walls and ceilings. Broken pipes can also lead to mold in areas where you wouldn’t typically find it.”

How to eliminate brown streaks on your bathroom walls

If you want to oust these brown streaks from your bathroom, there are a number of quick fixes and long-term solutions to try.

Apply ventilation: Tackle steam buildup by turning on a fan and keeping the door open, ideally during—and definitely after—showers.

Clean with ammonia: Mix warm water and household ammonia together, then use a clean cloth to wipe down the affected areas.

Clean with vinegar: For a more natural solution, mix one part white vinegar with seven parts water and wipe down your ceiling and walls.

Contact a plumber: If you suspect your spots are the result of leaky pipes, don’t try to deal with the issue yourself. Get in touch with a licensed plumber who can investigate and make any necessary repairs.