How do I get white clothes white again?

Whites go grey from underdosing, overloading and hard water rather than from age — and the fix is usually the wash routine plus an oxygen bleach soak.

Difficulty: beginner
Time: 40 min
Read: 4 min
Safety: warning

Short answer

Soak overnight in oxygen bleach powder and warm water, then wash whites alone at sixty degrees with a full dose of powder detergent and no overloading. Line dry in sunlight. Chlorine bleach yellows synthetics and is rarely the right answer.

Whites go grey for mechanical reasons, not because white fades. Grey comes from dye and soil redeposited from the wash water, from detergent starved by hard water minerals, and from a drum too full for anything to rinse. Yellowing is different: it is body oil oxidising, or chlorine bleach reacting with synthetics.

Safety

Chlorine bleach must never be combined with any acid — vinegar, lemon, limescale remover or descaler — or with ammonia or any ammonia-based cleaner, because both combinations release toxic gas within seconds. Use it in a ventilated room with gloves, and never on wool, silk, elastane or anything other than white cotton or linen. Oxygen bleach is safer and works on more fabrics.

What you'll need

Oxygen bleach powder
Powder detergent
A water softener additive, in hard water areas (optional)
A washing line

Step by step

Work out whether it is grey or yellow.Grey means soil redeposition and underdosing. Yellow means oxidised body oil, or chlorine bleach damage on a synthetic. They need different treatments.
Wash whites on their own.Every coloured item releases a little dye, and white fabric picks it up. Mixing a white shirt into a dark load once will grey it measurably.
Soak overnight in oxygen bleach.A full scoop in warm water, everything submerged, left eight hours. It is the single most effective treatment and it is safe on colours and most fabrics.
Use powder detergent rather than liquid.Powder for whites usually contains oxygen bleach and optical brighteners; liquid generally does not, because they are unstable in solution.
Dose for your water hardness.Hard water minerals consume detergent before it reaches the fabric. Underdosing in a hard area is the commonest single cause of grey washing.
Do not overload the drum.Clothes need room to move through the water. A packed drum cannot rinse, so soil suspended in the water settles back onto the fabric.
Wash at sixty degrees.Whites are the one category where a hot wash earns its cost, both for body oil and for the machine's own hygiene.
Line dry in direct sunlight.Ultraviolet light bleaches white cotton gently and effectively. A sunny afternoon does more for a white shirt than most products.
Keep chlorine bleach for white cotton only.It yellows polyester and destroys wool, silk and elastane. On white cotton, diluted, occasionally, it works — never mixed with anything else.
Run a maintenance wash on the machine.A dirty drum redeposits everything it holds. Ninety degrees empty, monthly, plus cleaning the seal and drawer.

Tips

A scoop of soda crystals in the wash softens hard water and lets the detergent work properly. It is cheap and it makes a visible difference in hard water areas.
Bluing agents work by adding a trace of blue to counteract yellow. They are an optical trick rather than a clean, and they must be diluted properly or they stain.
Store white items away from light in a wardrobe. Long-term light exposure yellows stored cotton, particularly if it is starched.

Common mistakes

Using chlorine bleach on white polyester or a blend — It reacts with the synthetic fibre and produces a yellow that gets worse with each application, and it is not reversible. Oxygen bleach is the correct choice for anything that is not pure cotton.
Adding more detergent to a full drum — The problem is that nothing can rinse, so extra detergent makes it worse. Half the load and the right dose beats a full load and a double dose every time.

If it doesn't work

Whites uniformly dull and grey

Cause: Underdosing, hard water or overloading — Fix: Overnight oxygen bleach soak, then a sixty degree wash with the hard-water dose of powder, at half the usual load size.

Yellow patches under the arms

Cause: Antiperspirant reacting with sweat — Fix: Vinegar soak then bicarbonate paste, and never chlorine bleach on this stain — it darkens it.

White synthetic gone yellow all over

Cause: Chlorine bleach used on polyester — Fix: Not reversible. Use oxygen bleach and sunlight on synthetics from now on.

Whites come out worse than they went in

Cause: Dirty machine redepositing soil — Fix: Empty ninety degree maintenance wash, clean the door seal, drawer and pump filter, then rewash.

Questions people ask

Does the dishwasher tablet trick work?

Boiling whites with a dishwasher tablet works because the tablet contains oxygen bleach and strong alkaline builders. Straight oxygen bleach powder does the same thing more controllably and without the boiling.

What are optical brighteners?

Compounds that absorb ultraviolet light and re-emit it as visible blue, making fabric look whiter than it is. They wash out, which is why whites look worse when you switch to a detergent without them.

Can I whiten wool or silk?

Not with either kind of bleach — both damage protein fibres. Use a wool-safe detergent, wash promptly, and accept that natural yellowing of old wool is generally permanent.