Washing Soda (Sodium Carbonate)

Chemically, washing soda is sodium carbonate, Na₂CO₃. It should not be confused with baking soda (sodium bicarbonate, NaHCO₃) or caustic soda (sodium hydroxide, NaOH). All three are alkaline, but they sit at very different points on the pH scale and do different jobs. A 1% solution of sodium carbonate sits at roughly pH 11, which is what gives it its water-softening and grease-cutting power.

That same strength is why it earns its place in the laundry. In hard-water areas, minerals in the water bind up your detergent so it cannot lather and clean properly. Washing soda softens the water first, so the detergent is free to do its job, which is why a scoop added to a heavily soiled load makes a noticeable difference.

• Softens Hard Water: Binds the minerals in hard water so your detergent can lather and clean properly.
• Boosts Your Detergent: Half a cup added to a wash lifts grease, oil and wine stains from heavily soiled loads.
• Builds Laundry Powders: A core ingredient in homemade laundry powder, pairing well with citric acid.
• Cleans Hard Surfaces: Works as a basic heavy-duty cleaner for most surfaces (avoid aluminium and fibreglass).
• Raises Pool pH: The standard product for lifting swimming pool pH when it drifts too low.

Laundry

• Add about half a cup to the drum with your normal detergent. Use a little more in hard-water areas.
• It dissolves best in warm water.
• For a homemade laundry powder, use it as the water-softening base.

Surface Cleaning

• Dissolve a few tablespoons in warm water to make a heavy-duty cleaner for greasy surfaces.
• Do not use on aluminium or fibreglass, as it will scratch and mark them.

Swimming Pool pH

• Add small amounts to raise pH when it reads too low, following your pool test kit and dosing guidance.
• A little goes a long way, so a bulk bag lasts a full season.

Chemical Information

• Chemical name: Sodium carbonate
• Also known as: Washing soda, soda ash
• Formula: Na₂CO₃

Physical Characteristics

• Appearance: White granular powder
• Solubility: Dissolves readily in warm water
• pH: Strongly alkaline (about pH 11 in a 1% solution)

⚠️ Safety & Precautions

• Wear gloves and avoid contact with eyes when handling larger amounts.
• Keep away from aluminium and fibreglass surfaces, which it will scratch.
• Store in a sealed container in a cool, dry place.
• Keep out of reach of children.
• Classified as a dangerous good. Cannot be sent overseas or by express post within Australia.

What is the pH of washing soda?

A 1% solution of sodium carbonate sits at roughly pH 11, which makes it a strong alkali. That high pH is what gives it its cleaning and water-softening power, so wear gloves and keep it away from your eyes when handling larger amounts.

Can washing soda be used instead of baking soda?

Not as a direct swap. Washing soda is far more alkaline than baking soda, so it is too strong for baking and gentle uses. For baking and deodorising, use our bulk baking soda instead.

How much washing soda do I add to a load of laundry?

About half a cup per load alongside your usual detergent, and a little more in hard-water areas. It works best dissolved in warm water.

Is washing soda the same as soda ash?

Yes. Washing soda, soda ash and sodium carbonate are all names for the same compound, Na₂CO₃. Soda ash is the term used more in industry and pool care, washing soda is the common household name.

Will washing soda damage surfaces?

It cleans most hard surfaces well, but it will scratch and mark aluminium and fibreglass, so avoid using it on those. Test on an inconspicuous area first if you are unsure.