Bicarbonate of Soda in the Washing Machine: The Simple Laundry Trick

A single, straightforward powder can make all the difference.

You fill the machine, select a cycle, add detergent, fabric conditioner and perhaps laundry fragrance too – yet the towels still feel rough, the bedding smells only reasonably fresh, and the drum itself has more of a musty cellar smell than a clean one. The answer is often not another specialist product, but a familiar kitchen cupboard staple: bicarbonate of soda, also known as sodium hydrogen carbonate.

What bicarbonate of soda actually does in a washing machine

Bicarbonate of soda is not a replacement for detergent. However, it can help your detergent work more effectively. It makes the water slightly more alkaline, allowing many stains and dirt particles to loosen more easily, so you can often use less detergent.

“Bicarbonate of soda makes detergent more effective, laundry softer and odours noticeably weaker – without creating a cloud of fragrance.”

The difference is particularly noticeable with towels and bedding. Fibres tend to feel less stiff, fabric drapes more softly and is less likely to feel scratchy. This can be especially pleasant against the skin.

Another major benefit is its effect on odours. Bicarbonate of soda does not disguise smells with perfume; instead, it reduces them chemically. Perspiration odour in sportswear, musty laundry left in the washing basket, or the slightly “cellar-like” smell of old towels are all situations where it comes into its own.

There are, however, plenty of myths around limescale. Bicarbonate of soda may limit the formation of deposits to some degree, but it is not a conventional descaler. Existing limescale can only be tackled with acidic products such as vinegar or citric acid. Bicarbonate of soda is clearly a helpful assistant, not a miracle cure.

How to dose bicarbonate of soda correctly in the washing machine

The key rule is this: bicarbonate of soda is a booster, not a complete laundry detergent. Continue using your usual detergent, although you can often reduce the amount slightly.

Everyday laundry: softer and fresher without overdoing it

• Load: around 5 kg of laundry
• Amount of bicarbonate of soda: 1 heaped tablespoon (approximately 25 g)
• Temperature: cycles between 30 and 60°C

Add this tablespoon either straight into the drum or to the detergent drawer. You can then often use a slightly smaller dose of detergent without compromising the cleaning result.

Strong-smelling sportswear: two-stage support

For technical tops, sweaty jogging bottoms or towels used at the gym, take a two-part approach:

• Add 1 tablespoon of bicarbonate of soda to the main wash, either in the drum or detergent drawer.
• Put another tablespoon in the fabric conditioner compartment so that it is released during the final rinse.

This tackles odours both during washing and while rinsing. With larger machines holding 7–8 kg, you can use up to 2 tablespoons in total when the drum is well filled.

“More than two tablespoons offers no benefit for the laundry – it only increases the risk of alkaline residue remaining on the fibres.”

Where to put bicarbonate of soda in the machine

The best place for bicarbonate of soda depends on the result you want:

• Directly in the drum: useful for powerful odours and stubborn dirt, as the powder acts directly on the clothes.
• In the detergent drawer: a sensible choice for long or eco cycles, because the bicarbonate of soda dissolves more gradually.
• In the fabric conditioner compartment: only if you deliberately avoid fabric conditioner and want laundry with as neutral and low-fragrance a finish as possible.

The final option can be particularly helpful for people with sensitive skin: less perfume and fewer fabric conditioner residues, while bicarbonate of soda still provides mild odour neutralisation.

A washing machine refresh: bicarbonate of soda as a care helper

The powder can benefit the appliance as well as your laundry. If the machine smells musty, or you notice a stale odour as soon as you open the door, run a “refresh cycle” every four to eight weeks:

• Put 100–150 g of bicarbonate of soda directly into the empty drum.
• Run a long cycle at a high temperature.
• Leave the door slightly open after washing so that the interior and rubber seals can dry.

For the detergent drawer and rubber seal, a mixture of lukewarm water and a little bicarbonate of soda is sufficient. Apply it with a cloth, leave it briefly, wipe again and rinse. This is not a substitute for descaling, but it can help with smells and deposits caused by detergent residue.

Bicarbonate of soda and vinegar: a strong pairing only when used separately

Social media is full of advice suggesting that you should pour bicarbonate of soda into the drum and vinegar into the machine for miracle laundry. This approach can work, provided the two substances do not come into direct contact.

The reason is simple: bicarbonate of soda is alkaline, while vinegar is acidic. If you combine them in one container or the same compartment, they react, fizz briefly and neutralise each other. What remains is essentially an unremarkable salt solution.

“Bicarbonate of soda and vinegar should not arrive in the same place at the same time; they need to work one after the other – alkaline first, then acidic.”

In practice, use them like this:

• During the main wash: use 1–2 tablespoons of bicarbonate of soda alongside detergent for cleaning and odour control.
• During the final rinse: add 100–200 ml of clear vinegar, or preferably a 15–20% citric acid solution, to the fabric conditioner compartment.

The second stage has a mild descaling effect and can replace standard fabric conditioner. Towels often feel softer afterwards, without a heavy layer of artificial fragrance.

Where bicarbonate of soda should not be used

Although bicarbonate of soda is useful for everyday laundry, it is only suitable to a limited extent – or not at all – for certain fabrics. Delicate fibres can react badly to alkaline solutions over time.

• Do not use bicarbonate of soda on: wool, silk or very delicate fabrics.
• Take care with: high-tech sportswear featuring specialist coatings or membranes.

Regular exposure to bicarbonate of soda may affect the protective surface of these textiles. Check the care label: if it refers to specialist detergents or particular membranes, it is better not to use bicarbonate of soda routinely.

People with sensitive skin may benefit from bicarbonate of soda because it can allow them to avoid fabric conditioner and strongly perfumed laundry fragrances. But if you use too much powder and the machine does not rinse thoroughly, residues can remain and cause irritation. If you experience itching or dry skin where clothes fit tightly, try using less bicarbonate of soda, select a cycle with an extra rinse, and avoid fabric conditioner entirely for a while.

Everyday questions about bicarbonate of soda in the washing machine

Can bicarbonate of soda replace detergent completely?

No, not for normally soiled or heavily soiled laundry. Bicarbonate of soda cannot break down grease and complex dirt to the same extent as a proper laundry detergent. A wash using only bicarbonate of soda may be enough for cleaning cloths or very lightly soiled items, but not for underwear, bedding or everyday clothes.

Can bicarbonate of soda damage the washing machine?

Not at the stated dose of one to two tablespoons per wash. On the contrary, it can provide a little support with machine care, especially where odours are concerned. Problems only arise if you use far too much powder and deposits build up.

Is supermarket bicarbonate of soda enough?

Yes, provided the pack states “sodium hydrogen carbonate” or “sodium bicarbonate” and it is a pure product. Specialist laundry products are often no different – simply packaged at a much higher price.

Why bicarbonate of soda is especially popular now

Many households are looking for ways to reduce costs and put fewer chemicals into the washing machine. Bicarbonate of soda fits this approach perfectly: it is inexpensive, versatile and has been a kitchen staple for decades. It was long a little-known bathroom tip, but it is now gradually finding its way into the laundry room.

People who begin washing with bicarbonate of soda often quickly notice a small change in their routine: less fabric conditioner, more attention to sensible dosing, and an occasional maintenance cycle for the machine itself. This can mean fewer trapped odours, fewer mixed products and laundry that often feels more natural – less heavily perfumed, but still pleasantly clean.

Ultimately, the advantage is practical: there is no need to add a seventh specialist product to the shelf. One household classic from the cupboard is enough to make your laundry, washing machine and nose happier, as long as you use it carefully and in moderation.