If you haven't heard of surfactant leaching, you're not alone. Neither had I until I started looking into why I had water streaks on my bathroom walls.
I partly knew the reasons why, but wanted to make sure I wasn't missing anything that could cause more damage in the long run such as damp. Plus, I wanted to know if there was a way to easily remove them without causing more marks.
While not as serious as water stains on walls, their unslightly appearance is something I'd rather avoid, so here's what's behind them and what you can do about it.
What causes water streaks on walls
Water streaks on walls are different to water stains in that they run in lines down the wall, unlike stains which tend to appear as brown patches in one spot.
In my particular case, they're thankfully not caused by anything too serious, but what could be causing the water streaks on your walls and do you need to be worried?
And, do water streaks look different depending on what's causing them. Building expert, Andy Simms from MyBuilder.com helps clear up what's behind the unsightly appearance of your walls.
1. Surfactant leaching
If your walls are looking streaky, there's something called surfactant leaching which may be causing the problem. But what is it?
“Surfactant leaching is when small, usually brown streaks appear on newly-painted surfaces, and it’s caused when rooms with poor conditions for paint drying, allow surfactants to rise to the surface," explains Andy Simms.
Surfactants are the water-soluble compounds which rise to the surface. The moisture causes these ingredients to 'leach' outwards, resulting in streaks running down your wall.
"It commonly occurs when poor drying conditions such as low temperature, high levels of humidity and low-level ventilation are in place," says Andy, "and it’s more likely to take place in bathrooms, kitchens, and laundry rooms, which are more prone to humidity and condensation, or any north-facing rooms, which are usually the colder rooms in your home."
The good news is, they aren't harmful and aren't caused by more serious problems such as mould or damp.
Even if you clean them off using the advice below, there's a chance you might encounter them again. So, to try and prevent them, make sure you've followed the instructions on the paint tin when painting your walls, and ensure you use the right type of paint in the correct location.
“While surfactant leaching can be difficult to prevent, there also are a few additional steps you can take to avoid cold or humid conditions in your home, which will minimise the chances of this happening," adds Andy.
- Ventilate: opening doors and windows, even for short periods will allow humidity to escape
- Avoid cold temperatures: ideally, you don’t want the room temperature to drop below 16°C while the paint is drying
- Avoid adding moisture: if you’re painting a bathroom or kitchen, avoid activities that will generate steam, like (showering or laundry) before the paint has fully dried. If this is unavoidable, consider using a dehumidifier after these activities
This Environvent bathroom extraction fan was rated best overall in our guide to the best bathroom extractor fans and can help keep your humid bathrooms drier
With over a decade of experience on the front line in construction as a multi-trader, Andy is uniquely placed in the construction industry to help bridge the gap between tradespeople and product managers with his role at MyBuilder.com
2. Using the wrong paint and poor ventilation
If you've got a 'sweaty toilet' or to use the correct term, condensation on your toilet, there's a fair chance you've got water streaks on your walls too.
Any condensation problems are caused by warm moisture droplets hitting a colder surface such as an external wall. If you don't have the best bathroom extractor fans or good bathroom ventilation measures in place, then in the same way condensation will gather on your windows and toilet, so it will linger on your walls.
Throw into the mix using non-specific bathroom paint then, like me, you'll soon start to see water streaks on your walls.
The only solution here is to repaint your walls with the correct product, something Beth Murton, editor of Homebuilding & Renovating had to succumb to as well.
"Like Sarah, I opted for a matt emulsion paint because I prefer that as a paint finish. Despite convincing myself it would be fine, our bathroom ventilation just couldn't handle the condensation, and the walls were streaky within weeks. In the end I had the paint re-mixed using a low-sheen base. It's resulted in no streaks and a surface that's much easier to clean."
So, in an ideal world, when next renovating your bathroom, as well as using the correct paint, it would also be wise to add in extra ventilation to help remove moisture more effectively.
In the meantime, make sure you undertake daily tasks such as house burping, or placing a dehumidifier outside the bathroom to draw out any excess water droplets.
Shop bathroom suitable paints
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Cleaning water streaks off walls
The first step when cleaning water streaks off walls, is understanding what paint finish you are tackling. In bathrooms, if you have used non-bathroom or non-wipeable paint, it will be hard to not remove some colour from your walls.
it also depends on how fresh your paint is warns Andy Simms. "If cleaning newly painted walls, it’s important to wait until the paint has completely cured," he advises. "This can take up to a week, to prevent smudging or peeling."
But, assuming you have used the correct paint, cleaning isn't too complicated a job.
"When removing any stains from painted walls, always start with the gentlest method," advises Georgina Shepherd, cleaning expert at Housekeep.com.
"For water marks, a little warm water mixed with mild dish soap on a microfibre cloth works pretty well. The trick is to keep the cloth damp, not soaked, and to avoid scrubbing too hard. After cleaning, dry the area immediately with a clean cloth."
Try this pack of Aieda microfibre cloths from Amazon for cleaning water streaks off walls. They come in different colours to help you separate them into dirty and clean cloths.
"If the water marks aren’t budging, a diluted vinegar solution (half water, half white vinegar) is very effective," she adds, "but I'd recommend testing it in a discreet area first, because vinegar can dull certain matte or flat finishes. Also, apply it with a cloth rather than spraying the wall directly for better control of how much solution is applied."
You could also try a Magic Eraser from Amazon to remove water marks from walls, says Georgina but err on the side of caution.
"These cleaners are micro-abrasive, so while they work well on satin or semi-gloss paint but can damage matte finishes by leaving shiny patches."
One final word of warning from Andy Simms? "It’s also recommended that you don’t just simply paint over the stains, as this won’t solve the problem, instead only trapping the oily residue of the streaks and causing them to worsen over time.”
Georgina is one of Housekeep.com's cleaning experts, providing knowledgeable advice to clients and staff on how to keep your home hygienically safe and sound.
If however you have water streaks on your walls despite using the right paint and the correct levels of home ventilation, do make sure you discount any serious problems such as a leaking roofs which could lead to more expensive roof leak repair costs.
Also ensure you give your loft insulation a good inspection, to check there isn't an issue with loft condensation tracking into the room where you've discovered water streaks on your walls.
