How to disinfect surfaces safely
Clean the surface first with detergent and water to remove dirt, then apply a disinfectant and leave it wet for the contact time on its label before wiping or letting it dry. Disinfectant poured on a dirty surface does little, and mixing cleaning chemicals can release toxic gases.
Last reviewed by the SANITIZER.PK team
Quick answer
- Clean first, then disinfect. Dirt blocks disinfectants.
- Leave the surface wet for the label's contact time.
- For general surfaces, WHO describes 0.1% sodium hypochlorite; most household bleach is around 5%, so about 1 part bleach to 49 parts water.
- Never mix bleach with ammonia, vinegar or acidic toilet cleaners.
Clean and disinfect in five steps
Protect yourself
Wear disposable gloves, open windows or doors, and keep children and pets away.
Clean with detergent and water
Wipe away visible dirt, grease and spills. Rinse if the detergent leaves a film.
Apply the disinfectant
Use a product made for surfaces, prepared as its label says. Wipe or spray so the whole surface is wet.
Wait for the contact time
Leave it wet for the time on the label, often several minutes. Wiping it straight off stops it working.
Rinse food-contact surfaces and wash hands
Rinse surfaces that touch food with clean water if the label says so, remove gloves correctly and wash your hands.
Which disinfectant for which surface?
| Surface | Suitable option | Notes |
|---|---|---|
| Floors, washroom surfaces, tiles | Diluted bleach or a labelled surface disinfectant | Bleach can fade fabrics and corrode metal |
| Door handles, switches, desks | 70% alcohol wipes or labelled surface disinfectant | Keep alcohol away from flames |
| Phones, keyboards | 70% alcohol wipe, lightly damp, device switched off | Check the device maker's advice |
| Kitchen counters, chopping boards | Food-safe sanitizer or diluted bleach, then rinse | Follow the label for food-contact use |
Diluting household bleach for general surfaces
Check the sodium hypochlorite strength on the bottle, as it varies between brands. For a bleach of about 5%, mixing 20 ml of bleach into 1 litre of water gives roughly 0.1%, the strength WHO describes for general environmental surfaces. Use cold water, make a fresh mix each day and label the bottle.
Never mix these
- Bleach and ammonia (found in some glass cleaners): releases toxic chloramine gas.
- Bleach and acids such as vinegar or many toilet cleaners: releases chlorine gas.
- Bleach and alcohol: can form harmful compounds.
- If anyone feels breathless, coughs or has burning eyes after mixing, move them to fresh air and get medical help.
Sources and standards referred to
- World Health Organization, guidance on cleaning and disinfection of environmental surfaces.
- Product labels: always follow the manufacturer's dilution and contact time.
This guide is general information about hygiene products, not medical advice. For a health condition, speak to a doctor or pharmacist.
Frequently asked questions
Can I use hand sanitizer on surfaces?
It is not designed for surfaces and is costly for the job. Use a surface disinfectant or 70% alcohol wipes for small items.
How often should office surfaces be disinfected?
Clean high-touch surfaces such as door handles, lift buttons and shared desks at least daily, and more often during outbreaks of illness.
Is boiling water a disinfectant?
Very hot water helps clean, but it cools quickly on a surface and is not a reliable disinfectant for counters or floors.
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