Disinfection
Dwell time is the whole job, and most contracts never mention it
An EPA registered disinfectant only works if the surface stays visibly wet for the full contact time on its label. Here is how that fails in practice and what to write into your scope.
A disinfectant is a pesticide. Its label is a legal document. The contact time printed on that label is not a suggestion about how long to be thorough, it is the tested period the surface must stay visibly wet for the kill claim to hold. Miss it and you have cleaned the surface, not disinfected it.
What the label actually requires
Every EPA registered disinfectant carries a registration number and a master label. The label states the organisms the product is registered against, the dilution, the personal protective equipment, and the contact time, sometimes called dwell time, for each claim. The same product can carry a one minute claim against one organism and a ten minute claim against another.
The requirement is that the surface remains visibly wet for the whole period. On a warm stainless handrail in a corridor with air movement, a light spray can flash off in under two minutes. If the label asks for four, the job is not done and no amount of wiping afterwards fixes it.
The EPA lists a facility manager should know
The EPA publishes lists of registered antimicrobial products by pathogen. Four come up constantly in commercial and healthcare cleaning.
| List | Registered against | Where it shows up |
|---|---|---|
| List N | SARS-CoV-2 | Office, education and general commercial disinfection scopes |
| List K | Clostridioides difficile spores | Healthcare, long term care, any facility with a C. diff protocol |
| List G | Norovirus | Food service, education, cruise and hospitality |
| List H | MRSA and VRE | Healthcare, athletics and locker rooms, fitness |
Where it goes wrong on a real site
- One product is used for every claim in the building, including ones its label does not cover.
- A concentrate is poured by eye instead of run through a dilution controlled dispenser, so nobody knows the actual ratio.
- The technician sprays and wipes in one motion, which is cleaning, not disinfection.
- The label calls for a pre-clean on a soiled surface and nobody does it, so organic soil neutralises the active ingredient.
- The contract says "disinfect high touch points daily" and stops there, so no one is accountable for a number.
What to write into your scope of work
Name the requirement rather than the outcome. A scope that survives an audit says which product class is approved for which claim, that dilution is dispenser controlled, that the surface is kept visibly wet for the label contact time, and that product, dilution and wet time are logged per round.
Then ask your vendor for one month of those logs before you renew. If they cannot produce them, the line in the contract was decorative.
About this article
Written for a demonstration website. Yolanda Berrios is a fictional person and Meridian Facility Services is a fictional company. The operational guidance reflects real commercial cleaning practice, and every figure given as a range is a range because the real answer is building specific.