Steam cleaning sanitises without chemicals

Does it work?

Unresolved

The mechanism is established and the delivery is not. That heat disinfects is established; that a domestic steam cleaner achieves disinfection in ordinary use is not, because no authoritative source measures it. The principle alone does not carry the practice.

This is a verdict on whether the technique is effective. Whether it is safe on a particular surface is a separate question, answered below.

Where not to use it

Why it works

Heat denatures proteins and disrupts cell membranes, and above a threshold that depends on the organism and the exposure time this is lethal to micro-organisms — the principle behind autoclaving and thermal disinfection generally. Steam adds latent heat release on condensation, which delivers energy to the surface efficiently. The mechanism is therefore not in question. What is in question is whether the delivered temperature is maintained at the surface for long enough during a normal pass, given that the steam cools on contact, that the surface conducts heat away at a rate depending on its material, and that the operator controls the dwell time by hand. Cleaning — the removal of soil — is a separate matter, and steam plus mechanical action does that well.

Background

Steam cleaners are marketed on a genuinely attractive proposition: heat as a substitute for chemistry, with no residue and nothing to rinse. The underlying principle is sound — sufficient temperature for sufficient time denatures the proteins that micro-organisms depend on, which is the basis of every thermal sterilisation process there is. The two words carrying the weight are sufficient and time, and that is where the evidence stops. Disinfection is defined by contact time at an effective condition, and a steam jet moving across a surface delivers heat for a period that depends on the machine, the distance, the speed of the pass and what the surface is made of. No authoritative source establishes that domestic steam cleaning achieves disinfection under realistic use, and the fact that heat can disinfect does not establish that it does. Separately, steam is a burn hazard and drives moisture into porous materials and joints, which is the opposite of what mould prevention requires.

What it does not do

• No authoritative source establishes domestic disinfection performance in ordinary use
• Cleaning and disinfecting are different processes, and steam's effectiveness at the first says nothing about the second
• Steam drives moisture into porous materials and joints, which works against mould prevention rather than for it
• It is a burn hazard, and on cold glass or stone a hot jet is a thermal shock risk

What to use instead

• Detergent — A surfactant-based cleaner. The general-purpose answer for greasy and particulate soil, and the correct first choice far more often than any specialist product.
• Neutral cleaner — A near-neutral surfactant cleaner. The recommended answer for natural stone of every kind, and the least interesting product in the cupboard for good reasons.
• Soaking — Extending contact time so chemistry can do work that would otherwise need force. Often the difference between scrubbing and wiping.