A bowl of salt water by the window in winter: this simple trick works just as well as aluminum foil in summer

The very first time I noticed it, I genuinely assumed my neighbour had left something out after making dinner.

A plain white bowl sat on her windowsill, filled with milky-looking water with a thick layer of salt settled inside. Outside, the street was locked in that flat, bone-cold grey that comes with mid-winter. Yet inside her flat the panes were clear - no misting, no trails of water creeping down the glass. Meanwhile, my own windows were streaming with condensation.

When we had a cup of tea, she caught my confused stare and chuckled. “It’s my winter take on the aluminium foil trick,” she said, nodding at the bowl. “In summer, foil. In winter, salt water.” It sounded like one of those old-school tips you hear once and forget. Still, over the next few days I kept thinking about it: how could something so basic make such a noticeable difference?

Why winter windows “sweat” - and where a salty water bowl fits in

On frosty mornings, your windows act like a display board for what’s happening indoors. Warm air loaded with moisture - from showers, cooking and even just breathing - meets cold glass. The vapour turns into tiny droplets, which merge into streaks and slide down the pane. The frame begins to darken, paint can start to lift, and in the corners mould finds a foothold.

That water isn’t seeping in from outdoors. It’s your own indoor humidity condensing because it has nowhere else to go. In the warmer months, people sometimes use the aluminium foil trick to reflect sunlight and reduce heat build-up. In winter, the problem is less obvious but just as persistent: moisture trapped inside, clinging to the coldest surfaces. Windows often become the weak point - and that’s exactly the spot where a bowl of salty water can help.

Imagine a small city flat with radiators hissing and a clothes airer set up by the window. A couple work from the kitchen table, charging leads weaving between mugs of coffee. By 9 am the glass is so fogged they can barely make out the street. They crack a window open “for five minutes”, the room turns icy, and they shut it again almost immediately.

They do what most people do: kitchen roll, an old towel, wiping the panes each morning. By the third week, the silicone seal along the bottom edge starts to blacken. Then a friend sends a photo: a bowl, a handful of coarse salt, a splash of water. “Put this by the window,” she messages. They laugh - it looks like a supermarket science experiment - but they try one bowl on each sill.

Nothing miraculous happens on day one. But by the fourth morning, the change is hard to ignore. The edges still mist slightly, yet the heavy streams of water have largely disappeared. The towel they relied on stays mostly dry. Looking closer, they notice the salt has built a crust, like compacted snow. Guests wouldn’t spot the difference - but for them it feels like taking back control of their home.

There’s no mystery involved: it’s simply physics and chemistry. Salt is hygroscopic, meaning it attracts and holds onto water. In practical terms, salty water draws moisture from the surrounding air into the brine.

With less water vapour available to condense on the glass, the window has less to “catch”. This won’t transform the humidity of an entire house, but on a windowsill - right beside a cold pane - it can create a slightly drier micro-area. Think of it as placing a small, low-cost dehumidifier exactly where the problem shows up.

A quick add-on: check your humidity (and why it matters)

If you want to know whether you’re fighting a small issue or a bigger one, a cheap digital hygrometer can be surprisingly helpful. Many homes feel comfortable at roughly 40–60% relative humidity; when levels sit higher for long periods, condensation and mould become much more likely, especially on cold surfaces like windows and outside walls.

If your readings are consistently high, the salty water bowl is still worth trying - but it should sit alongside basics such as using extractor fans, opening trickle vents (if you have them) and avoiding drying multiple loads of washing indoors without ventilation.

How to use salty water by the window in winter - the simple method (salty water bowl)

The routine is almost soothing in its simplicity. Choose a bowl you don’t mind getting marked over time. Fill it about halfway with tap water, then add a generous handful of coarse salt. Give it a brief stir. You’re aiming for some salt to dissolve while some remains visible at the bottom. The water should look slightly cloudy, like seawater in a shallow rock pool.

Set the bowl on the windowsill as close to the glass as you can without risking splashes onto the frame. For a small room, one medium bowl per window is usually plenty. If you’ve got a large bay window, two smaller bowls - one at each end - often work better than a single large one.

About once a week, take a look: if the salt has fully dissolved or a thick, hard crust has formed, replace it. Pour away the liquid, rinse the bowl quickly, and mix a fresh batch.

Small things that stop the trick working (and how to avoid them)

A few common mistakes lead people to conclude “it doesn’t work”, when the set-up is the real problem:

• Hiding the bowl behind heavy curtains or blinds. The brine needs access to the room air; smother it with fabric and the effect drops sharply.
• Expecting a fix for a seriously damp home. If you’re drying three loads of washing in a tiny lounge with little ventilation, even multiple bowls won’t rescue the windows. You still need small habits: brief airing, using the extractor fan while cooking, and not pushing furniture tightly against cold external walls. Let’s be honest: hardly anyone does this perfectly every day - but doing it a bit more often, plus the bowls, can tip things in your favour.
• Forgetting salt has a limit. Once the solution is saturated, it can’t take on much more moisture. That’s when people say, “It helped at first, then it stopped.” The unglamorous answer is simply to change the mixture regularly - especially in damp-prone spaces such as bathrooms and compact kitchens.

“It’s not witchcraft,” laughs Claire, 39, who rents in a draughty old building. “It’s just the only cheap thing that stopped my bedroom window from crying every morning.”

Her experience matches what you’ll see across forums and social feeds: photos of bowls on sills, on top of radiators, and tucked into corners where mould likes to start. Some people also combine it with the summer standby - the aluminium foil trick on glass (or external shutters) in July to bounce heat away - and then switch to bowls of salt water in January to keep humidity under control. In both cases, the idea is the same: protecting the thin boundary between indoors and outdoors.

Practical tips to get the best results

• Use coarse salt rather than fine table salt; it tends to last longer and dissolves more slowly.
• Start with the coldest, most misted windows instead of spreading bowls throughout the home.
• Check for mould on frames and nearby walls, and wipe it away early before it spreads.
• Combine the bowls with short, daily ventilation rather than relying on them alone.
• Keep pets and small children away - salty water is not for curious mouths.

A small caution: protect your sill and fittings

Salt can be messy. If your sill is painted wood, MDF, or close to metal fittings, put the bowl on a saucer or coaster and wipe up any splashes promptly. Brine can leave marks and may encourage corrosion on metal over time if it’s allowed to sit.

From small hacks to a calmer way of getting through winter

There’s something comforting about quiet, homemade fixes. A bowl of salty water doesn’t announce itself as a “smart home” solution or a connected gadget. It simply sits there, doing a job you barely notice - until you remove it and the windows start running again. In a season of short days and high energy bills, that kind of low-effort help can feel like its own form of warmth.

Most of us recognise the moment when the home seems slightly hostile: dripping panes, radiators humming, heavy air after a shower. These small measures won’t turn an older flat into a perfectly sealed, fully insulated retreat - but they can improve day-to-day living. A drier pane. A frame that stays cleaner for longer. Less wiping, less scrubbing, less worrying about the next patch of mould.

Some people will try the bowl and stick with it. Others will treat it as a modest extra alongside bigger steps: improving window seals, checking vents, adding insulation, or running a proper dehumidifier in the dampest room. Either way, the underlying principle remains - just like the aluminium foil trick in summer and salt water in winter: you don’t have to accept the season exactly as it is. You can nudge your home’s microclimate, one windowsill at a time - and pass the tip on to the next person who wonders why your windows have stopped “crying”.

Key point	Detail	Why it matters to you
Salty water absorbs moisture	Salted water is hygroscopic and draws humidity from the air near cold windows	Helps cut condensation without buying expensive devices
Placement makes a difference	Bowls should sit close to the glass and mustn’t be hidden behind curtains	Improves the real-world impact on misted windows
Routine, not a miracle	Replacing the salty water regularly and airing rooms still matters	Reduces mould risk, protects frames, and keeps the home more comfortable

FAQs

• Does a bowl of salty water really stop window condensation? It won’t remove condensation entirely, but it can reduce it noticeably on the specific windows where you place the bowl, particularly in small, closed rooms.
  
• What type of salt should I use for this trick? Coarse salt (cooking salt or rock salt) tends to work best because it dissolves more slowly and keeps drawing in moisture over time.
  
• How often should I change the water and salt? Typically every 7–10 days, or sooner if the salt has fully dissolved or formed a thick, hard crust.
  
• Is this enough for a very damp home? No - in very humid properties it’s only a supporting measure; you’ll likely need proper ventilation, possibly a dehumidifier, and sometimes insulation or repairs.
  
• Can I use the same bowl trick in summer? Yes, it can still absorb humidity in summer, but during hot spells the aluminium foil trick or shading is usually more effective for reducing heat than salty water alone.