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

A simple powder can make all the difference.

You fill the machine, select a cycle, add detergent, fabric conditioner and perhaps even laundry fragrance – yet towels still feel scratchy, bed linen smells merely acceptable and the drum itself has more of a cellar smell than a fresh one. The answer is often not another specialist product, but an old kitchen cupboard staple: bicarbonate of soda, also known as sodium bicarbonate.

What bicarbonate of soda actually does in the washing machine

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

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

The difference is especially noticeable with towels and bed linen. Fibres feel less stiff, the fabric drapes more softly and is less likely to feel rough. This is particularly more comfortable against the skin.

Another major benefit is odour control. Rather than masking smells with perfume, bicarbonate of soda chemically reduces them. Sweat odours in sportswear, musty laundry left in the washing basket or the slightly “cellar-like” smell of old towels are exactly where it works best.

There are, however, plenty of myths around limescale. Bicarbonate of soda may slightly limit the formation of deposits, but it is not a conventional descaler. Existing limescale requires an acidic product such as vinegar or citric acid. Bicarbonate of soda is clearly a helpful addition, not a miracle cure.

How to dose bicarbonate of soda correctly in the washing machine

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

Standard laundry: softer and fresher without overdoing it

• Load: around 5 kg of laundry
• Amount of bicarbonate of soda: 1 heaped tablespoon (approx. 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 lower detergent dose without compromising cleaning results.

Strong-smelling sportswear: double support

For technical tops, sweaty jogging bottoms or towels from the gym, use a two-stage approach:

• Add 1 tablespoon of bicarbonate of soda to the main wash (in the drum or detergent drawer).
• Put 1 further 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 (7–8 kg), you can use up to 2 tablespoons in total when the drum is well filled.

“More than two tablespoons does nothing for the laundry – it merely 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 what you want it to do:

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

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

A care treatment for your washing machine: bicarbonate of soda as a maintenance aid

The powder can benefit the appliance itself 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 “treatment cycle” every four to eight weeks:

• put 100–150 grams of bicarbonate of soda directly into the empty drum;
• run a long programme at a high temperature;
• leave the door ajar after washing so 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 enough. Apply it with a cloth, leave it briefly, wipe again and rinse. This does not replace a descaler, but it helps tackle smells and deposits caused by detergent residues.

Bicarbonate of soda and vinegar: a strong combination only when kept apart

A social-media tip recommends tipping bicarbonate of soda into the drum and vinegar into the machine to create miracle-clean laundry. This approach can work, provided the two substances do not directly “meet”.

The reason is straightforward: 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 one another. What remains is essentially an unremarkable salt solution.

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

In practice, use them like this:

• During the main wash: add 1–2 tablespoons of bicarbonate of soda with the 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 replaces conventional fabric conditioner. Towels will often feel softer without that heavy, artificial layer of fragrance.

Where bicarbonate of soda should not be used

Useful as it is for everyday washing, bicarbonate of soda is only suitable to a limited extent – or not at all – for certain fabrics. Sensitive fibres can react poorly to alkaline solutions over time.

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

Regular contact with bicarbonate of soda can affect the protective surface of these textiles. Check the care label: if it mentions 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 well, residues can remain and may in turn irritate the skin. If you experience itching or dry skin where clothing fits tightly, try using less bicarbonate of soda, choose a cycle with an extra rinse and avoid fabric conditioner altogether for a while.

Everyday questions about bicarbonate of soda

Can bicarbonate of soda replace detergent completely?

For normally soiled or heavily soiled laundry, no. Bicarbonate of soda does not remove grease and complex soiling to the same extent as a proper detergent. A wash using only bicarbonate of soda may be sufficient for cleaning cloths or very lightly soiled items, but not for underwear, bed linen 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 offers some light maintenance support, especially for odours. It only becomes problematic if you use far too much powder and residue builds up.

Is bicarbonate of soda from the supermarket sufficient?

Yes, provided the pack states “sodium bicarbonate” or “sodium hydrogen carbonate” and it is a pure product. Specialist laundry products are often nothing different – simply packaged at a much higher price.

Why bicarbonate of soda is so popular right now

Many households are looking for ways to cut costs and pour fewer chemicals into the washing machine. Bicarbonate of soda fits that thinking perfectly: it is inexpensive, versatile and has been a kitchen staple for decades. It was long considered a bathroom insider tip, and is now gradually making its way into the utility room.

Anyone who starts washing with bicarbonate of soda will usually notice that their routine soon changes: less fabric conditioner, more attention to sensible dosing and an occasional maintenance cycle for the machine itself. This can mean less trapped odour, fewer product combinations and laundry that often feels more natural – less heavily perfumed, but still pleasantly clean.

The practical advantage is simple: 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, machine and nose happier, provided you use it purposefully and in moderation.