To use borax substitute in laundry, add about 1–2 tablespoons to the drum of your washing machine along with your usual detergent, then wash as normal. For heavily soiled or greying whites, dissolve the same amount in a bucket of warm water and pre-soak the items for a few hours first. Borax substitute is the legal household replacement for borax in the UK: it softens hard water so your detergent can work better, and it is gentle enough for most everyday cotton and synthetic loads.
This guide covers how much to use, when it helps most, which fabrics to avoid, how to store it, and why pure borax is no longer sold for home laundry.
What is borax substitute?
Borax substitute is a blend of sodium carbonate (washing soda) and sodium bicarbonate (bicarbonate of soda), sometimes sold as sodium sesquicarbonate. It contains no boron. In water it forms a mildly alkaline solution, similar in strength to borax, which is why it can do most of the same jobs around the house.
Genuine borax (sodium tetraborate) is a different chemical. In Great Britain it is classified as toxic to reproduction, so it is no longer supplied to the general public as a household laundry product. If you want the background, read Is borax banned in the UK? and our comparison borax vs borax substitute.
Why add borax substitute to your wash?
It softens hard water
Hard water contains dissolved calcium and magnesium. These minerals react with detergent and reduce the amount available to lift dirt, which is why washing in hard water areas can leave whites looking dull and towels feeling stiff. The carbonate in borax substitute binds calcium and magnesium so they drop out of solution, leaving softer water for your detergent to work in. If you are not sure how hard your water is, your water supplier publishes hardness information for your postcode.
It boosts your normal detergent
Borax substitute is a laundry booster, not a detergent. It does not replace your washing powder or liquid; it helps it perform. Many people find they get cleaner results at lower temperatures when they add a booster, particularly in hard water.
It helps with greying whites and everyday odours
A pre-soak in a borax substitute solution helps loosen ground-in dirt on sports kit, tea towels, bedding and work clothes before the main wash.
How much borax substitute to use
Always check the dosage instructions on your pack first, as blends differ. As a general guide for a standard household load:
| Job | Amount | How |
|---|---|---|
| Normal wash, soft water | 1 tablespoon | Add to the drum with your detergent |
| Normal wash, hard water | 2 tablespoons | Add to the drum with your detergent |
| Heavily soiled load | 2 tablespoons | Add to the drum, choose a longer cycle |
| Pre-soak | 2 tablespoons per bucket (about 5 litres) of warm water | Dissolve fully, soak for 2–4 hours or overnight, then wash as normal |
Our borax substitute double pack (1800g) gives about 60 washes at a typical dose. More is not better: overdosing can leave a white residue on dark fabrics and will not make clothes any cleaner.
Step by step: adding borax substitute to a machine wash
- Sort your laundry as you normally would, by colour and care label.
- Measure the powder with a dedicated spoon or scoop that you keep with the laundry products, not a kitchen spoon.
- Put it in the drum before you load the clothes, or in the main wash compartment of the drawer if your machine manual allows powder there.
- Add your usual detergent at its normal dose.
- Wash at the temperature on the care label. Borax substitute dissolves at all normal wash temperatures, but dissolves fastest in warm water.
- Put the pack away straight after use (see storage below).
How to pre-soak with borax substitute
- Fill a bucket or sink with about 5 litres of warm water.
- Stir in 2 tablespoons of borax substitute until it has fully dissolved.
- Submerge the items and leave for 2–4 hours, or overnight for very greyed whites.
- Wring out and wash as normal with detergent. Pour the soak water down the sink with plenty of running water.
Wear household rubber gloves when your hands will be in the solution for more than a moment, as alkaline solutions can dry and irritate skin.
Fabrics to avoid
Borax substitute is alkaline, so it is best kept away from delicate protein fibres and special finishes:
- Wool, cashmere and silk: alkaline washes can weaken and felt these fibres. Use a dedicated wool or delicates detergent instead.
- Leather, suede and anything labelled dry clean only.
- Garments with special coatings, such as waterproof outdoor shells, unless the care label says otherwise.
- Bright or unusual dyes: if in doubt, test on an inside seam first.
Do not add vinegar to the same wash as borax substitute: the acid simply neutralises the alkali, so neither does its job.
Other household cleaning uses
The same pack is useful around the house. Dissolved in warm water, borax substitute can be used to wipe down sinks, tiles and grout, to soak greasy oven racks, and to freshen bins. Rinse surfaces with clean water afterwards, and avoid using it on aluminium, natural stone or waxed wood, which can be marked by alkaline cleaners.
How to store borax substitute safely
- Keep it in its original, labelled container, with the lid or seal closed.
- Store it in a cool, dry place. The powder absorbs moisture from the air and will form hard lumps if left open in a damp utility room.
- Keep it out of reach of children and pets, on a high shelf or in a cupboard with a child lock.
- Store it away from food, and never decant it into food containers, jars or unlabelled tubs.
- If it has clumped, break up the lumps in the closed bag; it is still usable once it dissolves.
Safety information
Borax substitute (sodium carbonate / bicarbonate) causes serious eye irritation. Avoid getting the powder or solution in your eyes; if you do, rinse cautiously with water for several minutes. Do not swallow. Avoid breathing in the dust when pouring. Keep out of reach of children.
Genuine borax (sodium tetraborate) is classified under GB CLP as Repr. 1B, hazard statement H360FD: may damage fertility, may damage the unborn child. It is supplied for professional and industrial use only and should not be used for household laundry. If you handle genuine borax at work:
- keep it out of reach of children;
- wear gloves and eye protection;
- do not swallow, and never use it in food, cosmetics or toys such as slime;
- avoid creating or breathing in dust;
- it should not be used by anyone who is pregnant or trying to conceive;
- store it in the original labelled packaging, away from food.
For full workplace guidance, see our borax safety, handling and storage guide.
Frequently asked questions
Can I use pure borax powder in my washing machine?
In the UK, pure borax (sodium tetraborate) is no longer supplied to the public for household laundry because it is classified as toxic to reproduction. For home laundry, use borax substitute, which does the same everyday jobs of softening water and boosting detergent.
How much borax substitute should I put in a wash?
About 1 tablespoon per load in soft water and 2 tablespoons in hard water, added to the drum with your usual detergent. Always check the instructions on your pack first.
Does borax substitute replace washing detergent?
No. Borax substitute is a laundry booster. Use it alongside your normal detergent, not instead of it.
Can I use borax substitute on wool or silk?
No. It is alkaline and can damage wool, cashmere and silk. Use a dedicated wool or delicates detergent for these fabrics.
How should I store borax substitute?
Keep it in its original labelled container, closed, in a cool dry place, out of reach of children and pets and away from food.
Sources
- ECHA (European Chemicals Agency), substance information for disodium tetraborate decahydrate (CAS 1303-96-4): harmonised classification Repr. 1B, H360FD. echa.europa.eu
- ECHA, substance information for sodium carbonate (CAS 497-19-8): Eye Irrit. 2, H319.
- HSE, GB CLP Regulation guidance. hse.gov.uk
Need a laundry booster for home? Our borax substitute range is made for everyday washing and cleaning. Working in a workshop, studio or lab? See our technical grade borax powder, supplied with a Safety Data Sheet for professional use.