Sunlight Saves One Mattress and Destroys Another

The short answer: how to dry a mattress is a race against a 48-hour clock, and what you are allowed to do depends on what is inside it. Press the water out mechanically with towels and your body weight first, because extraction beats evaporation by hours. Then move air across it with fans rather than heat. The part most guides get wrong is the heat: sunlight and a hairdryer are recommended everywhere and they will harden and yellow a latex mattress permanently, while high heat breaks foam down into lumps. And if the water was sewage, floodwater or has been sitting for two days, the honest answer is that the mattress is finished, whatever a mattress company’s blog tells you.

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What is inside decides what you can do

Almost every guide on this gives one method for one thing called a mattress. There are four common constructions, they dry at completely different speeds, and the advice that saves one damages another. Work out which you have before you touch it.

Innerspring: dries fastest, rusts quietly

Water runs through the open structure and drains toward the bottom rather than being held in place, so an innerspring mattress dries considerably faster than anything foam. Propping it on its side genuinely works, since gravity does part of the job.

The failure mode nobody mentions is that the springs are steel. Water that reaches them and sits there rusts them from the inside, and you will not see it until the mattress starts squeaking or sagging in a patch months later. So drying fast is not the same as drying completely, and an innerspring that got thoroughly soaked deserves more patience than its quick surface drying suggests.

Memory foam: holds water in the core

Foam is an open cell structure, which means it behaves like a sponge: it takes water in readily and gives it up reluctantly to air. Dense closed-cell foam holds moisture in the middle long after the surface feels dry, which is exactly how a mattress ends up smelling musty a week later.

This is the slowest construction to dry and the one where mechanical extraction matters most, because evaporation alone barely reaches the core. It is also the one high heat damages: foam breaks down at temperature and the result is a lumpy, permanently misshapen mattress.

Latex: heat is the enemy, including sunlight

This is the correction that matters most, because the standard advice is actively harmful here. Latex hardens and yellows when exposed to heat, which includes a hairdryer and includes putting the mattress out in the sun. Both of those appear as recommended steps in guides that do not distinguish between constructions.

Latex is also dense, so it dries slowly. The only safe method is extraction plus moving air at room temperature, with patience measured in days rather than hours. If your mattress is latex and you have already had it in the sun, check for stiffening and discolouration, because neither reverses.

Pillow-top and hybrid: the layer you cannot reach

A pillow-top has a quilted fibre layer stitched permanently to the surface, and that layer soaks up liquid like a sponge and cannot be separated from the mattress to dry on its own. It is the worst construction for a spill, because the wettest part is also the part with the least airflow.

Hybrids combine springs with foam layers, which means you get the foam drying problem on top of the spring rusting problem. Treat a hybrid as foam for method and give it the extra time an innerspring would not need.

So the sequence is the same for all four and the constraints differ. Extract mechanically, move air rather than heat, respect the 48-hour clock, and know before you start whether heat is merely unhelpful or genuinely destructive for what you own.

Work out your method in 3 taps

What it is made of, what got it wet, and how long ago. Those three decide whether you are drying a mattress or replacing one.

Construction by construction, what changes

The sequence is the same for all of them. The heat column is where the published advice becomes dangerous, and the last column is what nobody tells you to watch for afterwards.

The latex row is the one to act on. Two of the sources recommending sunlight and a hairdryer for drying a mattress do not mention construction at all, and following them on latex produces a mattress that is stiff and yellow and stays that way. If you do not know what yours is, check the label or feel the edge: latex is noticeably heavier and springs back faster than memory foam, which sinks slowly under a hand.

The drying sequence, in order

Extraction first, air second, patience third. Doing them in that order is the difference between a day and a week, and between a mattress you keep and one you put on the kerb.

1. Strip the bed immediately and get everything off. Sheets, protector, topper. Anything left on top holds moisture against the mattress and blocks the airflow you are about to need.
2. Press dry towels in with your body weight, not your hands. Stand on them if you can. Swap saturated towels for dry ones and repeat until nothing more transfers. This step removes more water than everything that follows, and it is the one people rush.
3. Extract with a wet dry vacuum if you have one. Run the nozzle slowly in overlapping passes. Unlike a household vacuum it is built for liquid and pulls moisture from several inches down, which is where towels cannot reach and where the mould starts.
4. Treat the cause if there was one. Enzymatic cleaner for urine, cold water and then enzymes for blood or milk, nothing at all for clean water. Use as little liquid as the job allows, since you are trying to remove water rather than add it.
5. Stand the mattress on its side and get air moving. Two fans creating a cross breeze beats one fan pointed at it. On edge, both large faces are exposed and gravity helps rather than working against you. Open the windows.
6. Add a dehumidifier in the same room with the door shut. A fan moves air but does not remove moisture from it, so in a closed room the air eventually saturates and drying slows. The two together are considerably faster than either alone.
7. Baking soda once the bulk of the water is gone. A thick layer over the damp area, left several hours or overnight, then vacuumed off thoroughly. It absorbs residual moisture and odour at the same time. Dry, never mixed into a paste.
8. Test before you make the bed. Press a clean dry towel firmly into several different areas. If it comes away damp anywhere, the water is still inside and the mattress is not ready, whatever the surface feels like.

One thing about cat litter, which two guides recommend spreading over the mattress. The physics is sound, since clay absorbs water well, and the practical objection is that you are pressing clay dust into the surface you then sleep on. It is a reasonable emergency measure for a large spill and it is not a step I would choose over towels and a vacuum.

What not to do, and who recommends it

Four things appear in published guides on this subject and range from useless to destructive. Two of them come from the same articles that give otherwise sensible advice, which is why they are worth naming.

A hairdryer, on any setting

Two guides recommend a hairdryer over the wet spots, one specifying a low cool setting. The problem is that a hairdryer is a heat source held close to one small area, and heat is what damages both foam and latex. Foam breaks down and comes back lumpy; latex hardens and yellows.

Even on a genuinely cool setting it is a poor tool, because it dries the surface fast while doing nothing for the core, which is the opposite of what a mattress needs. A room fan moves far more air over a far larger area and costs nothing to leave running for eight hours.

Sunlight, which is conditional rather than universal

Two sources recommend sunlight as a natural disinfectant and moisture-wicking tool, and a third states that heat sources including sunlight harden and yellow a latex mattress. Both are correct about different mattresses, which is exactly the problem with advice that does not name the construction.

Brief sun on an innerspring is fine and mildly useful. Sustained sun on foam is a risk and on latex it is damage. If you use it at all, keep it short, turn the mattress, and skip it entirely if there is any chance yours is latex.

Vinegar and baking soda together, for urine

One mattress manufacturer’s own guide recommends removing urine stains with a baking soda and vinegar solution. Those two neutralise each other on contact, producing water and sodium acetate, so the mixture cancels itself before it reaches the mattress.

Use them separately if you use them at all: an enzymatic cleaner for the uric acid, then dry baking soda afterwards for residual odour, vacuumed off once the mattress is dry. Never combined, and never expect a fizzing mixture to do anything a salt solution would not.

Bleach and ammonia

Both weaken and discolour mattress fabric by breaking down the fibres, and neither addresses the thing you actually care about, which is moisture inside the mattress rather than a mark on the ticking. Hydrogen peroxide has a legitimate role on blood and it bleaches, so it belongs on pale fabric with a spot test and nowhere else.

The tool that does the real work: a wet dry vacuum

Everything about drying a mattress comes down to how much water you remove mechanically before you rely on evaporation, and this is the only domestic tool that reaches past the surface. Unlike a household vacuum it is built to handle liquid, and it pulls moisture from several inches into the foam where towels physically cannot go.

That depth is the whole point. The mould clock runs on the water in the core rather than the water on the surface, so an hour with this at the start saves you a day of fans and considerably improves the odds the mattress survives at all.

Five gallons is the sensible domestic size, large enough for the water out of a mattress and small enough to carry upstairs. This one has a stainless tank rather than plastic, which matters if it lives in a garage between uses, and comes with the seven foot hose and nozzles you need to work slowly in overlapping passes.

Worth it or skip: Worth it if you have children, pets or a house where things get spilled, since it also handles sofa cushions, rugs, a wet basement and the car. Skip it for a small localised spill you have already blotted, where towels and a fan will finish the job.

Check the 5 gallon wet dry vacuum on Amazon

Three more, and one of them prevents all of this

A zippered waterproof protector, which makes this article unnecessary. A fitted protector covers the top; a zippered encasement seals all six sides, so a spill that runs down the edge cannot reach the mattress either. This one has a micro zipper with teeth too small for bed bugs to pass and a velcro seal at the end of the zip, plus a cotton terry top that does not rustle. One caution the maker states and people ignore: cool wash and tumble dry on low, because the waterproof layer is TPU and heat deforms it permanently. See the zippered protector →

A dehumidifier, because fans alone stop working. A fan moves air and removes no moisture from it, so in a closed bedroom the air saturates and drying slows to a crawl. This covers 1,000 square feet, which suits a bedroom rather than a house, runs quietly enough to leave on overnight, and has a continuous drain option so it does not need emptying every few hours. It is also the right tool for the latex case, where heat is forbidden and patience is the only method. See the 8 pint dehumidifier →

An enzymatic cleaner, for urine and anything organic. Uric acid crystals are why a mattress smells again on a humid day weeks after it was cleaned, and enzymes digest them rather than diluting them. Apply it, allow the stated dwell time rather than wiping it off after a minute, then extract and dry. It is the one product here that addresses a cause rather than a symptom. See the enzymatic cleaner →

The same drying problem at a smaller scale is in drying cushion foam properly, and the reason your windows fog while you do this is in where the water sits on your windows.

Dried it and something is wrong? 2 taps

The quiz above is for the first hour. This one is for afterwards, and it will tell you honestly when a mattress is finished rather than fixable.

People also ask about drying a mattress

How do you dry a mattress fast?

Extraction first, then airflow, and skip the heat. Press dry towels into the wet area using your body weight rather than your hands, standing on them if you can, and swap saturated towels for dry ones until nothing more transfers. A wet dry vacuum then pulls moisture from several inches down where towels cannot reach, which is the single biggest time saver available. Only then set up fans: stand the mattress on its side so both faces are exposed, create a cross breeze with two fans, and add a dehumidifier in the same room with the door shut.

Can you put a mattress in the sun to dry?

It depends what it is made of, which is why the advice online contradicts itself. Brief sunlight on an innerspring is fine and mildly useful. On latex it is genuinely damaging: heat makes latex harden and turn yellow, and neither reverses. On foam, prolonged heat breaks the structure down and the mattress comes back lumpy. Sunlight also only ever dries the surface, so a mattress can come in from the garden feeling dry with several litres of water still in the core.

How long does a mattress take to dry?

Anywhere from several hours to several days depending on construction and how much water is involved, and the deadline matters more than the duration: mould spores need roughly 48 hours of dampness to establish colonies in layers you cannot reach. An innerspring dries fastest because water drains through it. Memory foam and latex are the slowest, since dense foam holds moisture in the middle long after the surface feels dry. Test with a dry towel pressed firmly into several areas rather than judging by hand.

When should you throw a wet mattress away?

Three clear cases. If the water was floodwater or sewage, since those carry contaminants throughout the mattress and no domestic cleaning makes it safe to sleep on. If it has been damp for more than 48 hours and smells musty, because that means growth in layers you cannot reach. And if there are brown, black or green patches, which are established mould rather than staining. Yellow or tan marks without odour are usually old moisture or body oils and are cosmetic.

Mattress drying FAQ

Is a hairdryer ever a good idea?

No, even on a cool setting. It is a heat source held close to a small area, and heat damages both foam and latex, while the cool setting simply makes it a very inefficient fan. It also dries the surface fast while doing nothing for the core, which is the opposite of what a mattress needs. A room fan moves vastly more air over a vastly larger area for the cost of leaving it on overnight.

Does baking soda actually help?

Yes, at the right point in the sequence. Applied dry after the bulk of the water is gone, a thick layer left for several hours absorbs residual moisture and odour together, and then vacuums off. What it cannot do is handle a soaking, since a box of powder cannot compete with litres of water. And never mix it with vinegar, which several guides recommend and which produces salty water instead of two active ingredients.

Should I use cat litter?

The physics is sound, since clay absorbs water well, and two guides recommend it for a large spill. The objection is practical: you are pressing clay dust into the surface you then sleep on, and getting it all back out of a fibre or quilted top is harder than it sounds. As an emergency measure on a serious flood, reasonable. Ahead of towels and a wet dry vacuum, no.

Can I sleep on it if it is only slightly damp?

Better not to, and the reason is the clock rather than the discomfort. Body heat plus residual moisture plus a duvet on top creates exactly the warm damp conditions mould needs, and you would be doing that for eight hours. If the towel test picks up any moisture, sleep somewhere else for a night and keep the fans running.

How often should I flip my mattress?

Most modern mattresses should not be flipped at all, only rotated, because they are built with a designated comfort layer on one side. Flipping one of those puts you on the support core. Rotating head to foot every three to six months evens out the wear and is the right routine. Only a genuinely double-sided mattress, which is rare now, is meant to be turned over.

Will a mattress protector have prevented this?

A fitted protector covers the top and a zippered encasement seals all six sides, so the second one also catches liquid running down the edge. Either would have made this a laundry job rather than a drying job. The one thing to know afterwards is that the waterproof layer is TPU and heat deforms it permanently, so wash cool and tumble dry on low, which is what makes a protector suddenly leak after a year.

The mattress drying cheat sheet

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The Cozy Home Starter Checklist

A protector on the mattress and a towel in the airing cupboard turn a disaster into a wash cycle. This printable walks you through a home room by room, catching the small preparations that decide how bad the bad day is.

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Keep reading

• Four Different Things, and Two of Them Ruin a Machine
  The layer that would have made this a wash cycle instead, and why heat cracks the waterproof membrane that does the work.
• Washing Foam Is Easy. Drying It Is Where Sofas Die
  The same problem at a scale you can carry, including the bag and vacuum trick that compresses foam and forces water out of the core.
• Submerging It Is a Drying Question, Not a Washing One
  Foam small enough to press out and dry in a day, which is exactly why the rules differ from a mattress.
• Where the Water Sits Tells You Which Problem You Have
  Why your bedroom windows fog while you dry a mattress, and what indoor humidity should actually read.
• Cozy Bedding Ideas: The Complete Guide to a Dreamy Bed (2026)
  What goes back on once the mattress is dry, and how the layers work together rather than against each other.
• New Sheets Are Not Stiff. They Are Coated
  If you are replacing the bedding anyway, this is what to do with it before the first night.

Extract, ventilate, and know what you own

Drying a mattress is a race against a 48-hour clock, and most of the winning happens in the first hour. Press the water out with towels and your body weight, then reach the core with a wet dry vacuum, because evaporation alone barely gets an inch in. Everything after that is airflow and patience.

Where the published advice goes wrong is heat. Sunlight and a hairdryer appear in guide after guide with no mention of construction, and on latex they harden and yellow the mattress permanently while on foam they break the structure down into lumps. Brief sun on an innerspring is fine. Knowing which you own before you act is the difference between drying a mattress and ruining one.

Then be honest at the end. Floodwater, sewage, two days of dampness with a musty smell, or brown and black patches all mean the mattress is finished, and a lot of the reassuring advice on this subject is published by companies that sell mattresses. You spend a third of your life on this surface, which is a poor place to be optimistic.

A glass of water went over mine at eleven at night and I spent the next hour standing on towels in my socks. It was worth every minute, and a zippered protector would have made it a five minute job.