This is one ingredient I genuinely recommend having in your home, even though I don't sell it. It has a specific job, it does that job well, and once you understand how it works, you'll know exactly when to reach for it.

What is hydrogen peroxide?

Hydrogen peroxide is a colourless liquid that looks almost identical to water. Pour it into a glass and you wouldn't be able to tell them apart just by looking.

Chemically it's written as H2O2: two hydrogen atoms and two oxygen atoms. Water is H2O. The difference is a single extra oxygen atom.

That one extra atom changes everything.

One molecule away from water (a chemistry joke worth knowing)

There's a chemistry joke that goes: a man walks into a bar and orders H2O. His friend says, "I'll have H2O2 please." His friend dies.

It's a terrible joke if you don't know chemistry and a good one if you do. H2O2 is hydrogen peroxide, and the reason it can harm you when swallowed (while water obviously can't)  is exactly the reason it's useful as a cleaning ingredient.

That extra oxygen atom makes the molecule unstable. It wants to break apart. And when it does, it releases reactive oxygen that attacks bacteria, viruses, mould, and organic stains. It's essentially using oxygen itself as the active agent.

The other thing worth knowing: when hydrogen peroxide finishes breaking down, what's left is water and oxygen. Nothing harmful, nothing to rinse away. It simply becomes water.

How it's made

Hydrogen peroxide occurs naturally, our own immune cells produce it as part of the body's defence mechanism, and it's found in small amounts in rain water. But the version you buy is manufactured industrially.

Understanding the concentrations: 3% and 6%

The number on the bottle tells you what percentage of the solution is actually hydrogen peroxide. The rest is water.

• 3% is the standard pharmacy and first aid grade. It's what's been used on minor cuts and scrapes for generations. At this concentration it's stable, safe to handle with bare skin, and effective for household disinfecting and stain removal.
• 6% is stronger and more commonly found in the cleaning aisle or used in hair bleaching. It's more potent and requires a little more care, but it's still safe for household use when handled correctly.

For DIY cleaning, either works. The 6% acts faster and with more intensity; the 3% is gentler and more forgiving.

You may also come across 30% or 35% concentrations. These are industrial grades used in manufacturing and water treatment. They are not for household use, can cause serious chemical burns, and are genuinely dangerous to handle without proper equipment. Leave those alone entirely.

* You can normally purchase from the chemist or supermarket, we are not able to stock this.

How it works

When hydrogen peroxide comes into contact with organic material (bacteria, mould, blood, food residue) the breakdown process accelerates dramatically. The organic material effectively triggers it.

The reactive oxygen released during that breakdown process oxidises the cell walls of bacteria and fungi, destroys the proteins that make up viruses, and breaks down the chemical structures that give stains their colour. That's why it works across such a range of jobs: disinfecting, mould treatment, and stain removal all involve the same underlying mechanism.

Contact time matters. Hydrogen peroxide isn't instant. For disinfecting, it generally needs a few minutes of dwell time on a surface to be effective. Spray it on, leave it, then wipe away. Spraying and immediately wiping doesn't give it time to work.

It's a broad-spectrum disinfectant, meaning it's effective against bacteria, viruses, fungi, and spores. That makes it one of the more thorough options in a DIY toolkit.

Shelf life and storage

Hydrogen peroxide has a shelf life of roughly one to three years when unopened, and around six to twelve months once the bottle has been opened. The reason it degrades is the same reason it's useful: it's an unstable molecule that naturally breaks down over time.

Light, heat, and air all accelerate that breakdown. This is why it's always sold in opaque or dark-coloured bottles, and why keeping the cap sealed matters.

Store it in a cool, dark place away from direct sunlight. You don't need to refrigerate it, but avoid anywhere that gets warm like a hot cupboard or the inside of a car in summer will shorten its life considerably.

If you want to check whether an older bottle is still active, pour a small amount onto your palm. If it's still effective, you'll feel a very mild tingle or see a slight fizz. No reaction at all usually means it's broken down and become ordinary water. It's harmless at that point, but also useless.

Because it's classified as a dangerous good at higher concentrations and a poison even at household grades, always keep it in its original labelled container. Never decant into an unlabelled bottle. Store it out of reach of children and treat it with the same care you'd give any household disinfectant.

Household uses

The jobs hydrogen peroxide handles best are ones where hygiene and sanitising are the priority rather than just removing visible dirt.

• Kitchen: chopping boards (particularly after raw meat), sink basins, high-touch surfaces like taps and handles. Spray, leave for a few minutes, wipe clean.
• Bathroom: mould-prone grout, shower screens, toilet bowls, and surfaces where bacteria and mould build up. It's particularly useful in corners and around seal lines where mould tends to establish.
• Stain removal: blood, wine, coffee, and other organic stains respond well because the oxidation breaks down the compounds giving the stain its colour. Apply directly, let it bubble briefly, then blot and rinse. Test first on coloured fabrics — hydrogen peroxide can bleach them.
• Laundry: useful for whitening whites and treating organic stains before washing. Not suitable for coloured fabrics.
• Sponges and cloths: soaking in a diluted hydrogen peroxide solution helps disinfect and freshen items that collect bacteria quickly.
• High-touch surfaces: door handles, light switches, and shared surfaces during illness. A quick spray and wipe is effective and leaves no residue.

Never mix it with anything

Hydrogen peroxide should be used on its own.

Do not mix it with bleach. The combination produces chlorine gas, which is toxic and has no place in a household cleaning routine.

Do not mix it with vinegar. The combination creates peracetic acid, which is more irritating than either ingredient alone. It also doesn't clean better — it's just harsher. Use them separately, not together.

The practical rule is simple: spray, wait, wipe, done. No mixing needed, and no mixing recommended.

Surfaces to be careful with

A few surfaces don't respond well to hydrogen peroxide.

• Coloured fabrics: it bleaches. Always test an inconspicuous area first, and for anything you care about, don't risk it.
• Natural stone: marble, granite, and other porous stones can discolour or be damaged. Avoid.
• Copper and brass: oxidation can alter the finish. Not suitable.
• Mirrors and some glass coatings: some mirror backings are sensitive to oxidising agents. Stick to glass cleaners for mirrors.

Hydrogen peroxide vs sodium percarbonate

Both release hydrogen peroxide, but they behave differently, which makes them suited to different jobs.

Liquid hydrogen peroxide is ready to act immediately. Spray it on a surface, and it starts working on contact. It's the better choice when you need direct disinfection or immediate stain treatment.

Sodium percarbonate is a dry powder that releases hydrogen peroxide slowly when dissolved in water. That slow release makes it better suited to soaking — laundry, stained containers, deodorising bins, cleaning grout with a paste. The extended contact time makes it more effective in those applications.

Choose based on the job. Direct and immediate: hydrogen peroxide. Soaking and sustained action: percarbonate.

Eco profile

Hydrogen peroxide breaks down into water and oxygen. There are no synthetic residues, no harmful compounds left behind, and nothing that affects waterways or septic systems at household concentrations. It's one of the cleaner disinfecting options available, both in terms of what it does and what it leaves behind.