Why do my clothes smell sour after washing? And how you can freshen them up again

Laundry should be straightforward. Put the clothes and linens in the drum, load it up with detergent, and press start. This means that when laundry comes out smelling musty, it can be hard to put a finger on why.

Luckily laundry experts have made their fair share of laundry mistakes resulting in lingering odors and sour smells.

Here, they break down why your clothes smell sour after washing, and explain how to do laundry correctly to make laundry smell better again.

Why do my clothes smell sour after washing?

From dirty washing machines to the wrong detergent, there are several reasons why your clothes might smell sour after a laundry cycle.

1. They took too long to dry

One of the most common causes of musty, sour smells on clothing is the garments taking too long to dry, says Ken Doty, cleaning expert and COO of The Maids. ‘Ensuring that you're using effective drying methods and checking for clothes to be completely dry before you put them away will also help fight these musky odors.’

To dry clothes quickly, use a tumble dryer with the right temperature setting for your garments (checking the laundry symbols on the care tag), or turn to the benefits of air drying laundry, drying outside on a breezy, bright, low-humidity day or hanging the clothes on an indoor drying rack with good ventilation (close to a dehumidifier).

2. Your washing machine is dirty

If you haven't cleaned a washing machine in a while, then it is likely the culprit behind musty lingering odors.

Trish Duarte, a professional cleaner with 10 years of experience and franchise owner of MaidPro Temecula and Murrieta, says, ‘Trust me when I say that the inside of a washing machine drum can harbor a nightmarish kind of ick. If your washing machine is not cleaned regularly, dirt, grime, mold, and mildew can accumulate exposing your clothing to being washed in contaminated water.

‘Set a calendar reminder to wash your machine every one to three months depending on use. Here’s a DIY cleaning recipe I use. Fill your empty machine with hot water. Add one cup of Borax and one cup of Arm & Hammer Washing Soda [available at Walmart] to the hot water. Run the machine through a wash cycle.

‘If there is excessive debris (it looks like crumbs) left in the machine, repeat the process once more. Wipe out any remaining debris you see and leave the lid or door open to air dry.’

3. You used too much detergent

Laundry detergent, although essential to cleaning your clothes, is another very common cause of sour smells. Using too much detergent, or using a low-quality detergent, can lead to a build-up on your clothes and linens. This then creates sour smells. Luckily, cutting down on laundry detergent is an easy fix.

Trish Duarte, a professional cleaner, continues. ‘Sour smells can be the result of allowing bacteria to feed and multiply on all the organic matter that is still trapped in our clothing from using too much soap.

‘Using too much detergent makes it so the washer won't rinse out all the soap, leaving a residue on clothes. You may have felt that stiffness in your clothes or noticed a lot of suds during a wash. Perhaps even a white or gray film in the drum or on clothes. This residue traps dirt, oils, and body fluids, providing a breeding ground for bacteria.

‘Check your detergent’s instructions and use the recommended amount for your load size.'

4. Your clothes sat too long before washing

While it is more eco-friendly to ensure you have a full laundry load before running a laundry cycle, letting your clothes sit for too long in your laundry basket will cause them to develop stronger odors which are then harder to remove in the wash. Especially if you hide laundry baskets and your laundry is sealed in with a lid.

To counteract this, do laundry more frequently, bulking up laundry loads with items such as towels that need washing frequently to get rid of musty bathroom smells.

5. You overload your washing machine

Conversely, putting too much in a washing machine can also cause lingering smells. This common washing machine mistake not only prevents your clothes from being washed thoroughly, allowing dirt and detergent to remain trapped between your clothes in the machine but can damage your washing machine drum as wet, heavy clothes bang around and risk throwing it off balance.

6. You didn’t take your laundry out soon enough

While it can be tempting to leave your fresh laundry in the washer for a few hours when you have settled down cozy on the sofa, it is a common cause of sour smells on fabric.

Daniel Brown, US-based cleaning and laundry expert, and CEO of Handy Cleaners, says that leaving clothes sitting in the drum for just one or two hours can be enough to undo the hard work of the previous laundry cycle.

Take your laundry out of the machine as soon as the cycle is complete, and remember to always leave your washing machine door open to prevent musty smells from settling in your machine ready to muddy the next load.

7. There are lingering bacteria

If you have a clean washing machine and dry your clothes properly, but they still smell sour, then it might be a result of lingering bacteria, Trish Duarte, a professional cleaner, warns.

‘We all know that if clothes are left damp for too long, bacteria and mold can develop. But did you know that in ideal environments, they can double in number every 20 minutes? That’s going from a few hundred when the wash stopped, to millions within four to six hours. This rapid growth is why it’s important to remove clothes from the wash right away, as they can become a breeding ground for bacteria and mold within a very short period.’

As a result, it is important to use the right detergents at the right temperature to remove odor residues and kill lingering germs.

8. Hard water

Trish Duarte, a professional cleaner says, ‘In areas with hard water, minerals can accumulate on clothes that can trap dirt and bacteria. These minerals can also bind with detergent preventing it from being able to do its job.’ This then causes sour smells on clothes.

Trish continues, ‘Think of it like a swimming pool. Maintaining a pH-balanced pool is crucial for creating a clean and clear swimming environment that minimizes the growth of bacteria, sludge, algae, and mold. It’s important to create an environment where your washer can perform at its best to allow clothing to come out of each wash fresh and clean.’

While it can be tricky to fix hard water in your home, Trish recommends using a water-softening agent like Calgon, at Walmart, or a detergent designed for hard water. ‘Seventh Generation Free & Clear, also at Walmart, is an eco-friendly detergent formulated to be effective in various water conditions, including hard water.

‘When selecting a detergent for hard water, look for labels that mention "hard water" or "water softening" properties,’ she adds.

Like removing fishy smells from clothes, getting rid of sour smells in clothing isn’t too tricky. Fixing the main cause of the problem before washing the clothing with the right amount of detergent, the right kind of detergent, and allowing it to dry fully will help freshen it right up.