Every registered disinfectant has a number on its label that most people never read: the contact time, sometimes called dwell time. It’s how long a surface has to stay visibly wet with the product to kill the organisms the label lists. Spray a surface and wipe it straight away and it looks clean, but for most products it hasn’t been disinfected. This guide explains how disinfectant contact time works and how to tell whether your cleaning company is respecting it.
Where to Find the Contact Time
It’s in the directions for use on the label, usually listed per organism or per use. A product might kill one virus in one minute and need ten minutes for a particular bacterium. The longest time listed for the organisms you care about is the one that counts. In the US, disinfectants are registered with the EPA, and the EPA publishes lists of registered disinfectants for specific pathogens, with contact times for each product.
Contact times on common products range from about one minute to ten minutes. Healthcare settings tend to use products with shorter times, because a ten-minute wait on every surface isn’t practical in a busy practice.
Why Spray and Wipe Fails
Disinfection is chemistry, and it needs time. If the surface dries, or is wiped dry, before the contact time is up, the product stops working and some of the organisms survive. Three common mistakes:
- Wiping immediately. The most common one. The surface looks clean and smells of disinfectant, but the job hasn’t been done.
- Too little product. A light mist on a large surface dries in under a minute, especially with South Florida air conditioning running hard. The surface has to stay wet for the full time, which can mean reapplying.
- Disinfecting a dirty surface. Most disinfectants need a clean surface to work. Grime and residue protect the organisms underneath. Clean first, then disinfect, unless the label says the product does both in one step.
Cleaning, Sanitizing and Disinfecting Are Different
- Cleaning removes dirt and most germs from a surface with soap or detergent and water.
- Sanitizing reduces bacteria to a level considered safe, typically for food contact surfaces.
- Disinfecting kills the specific organisms on the label, if the label directions, including contact time, are followed.
An office breakroom counter needs cleaning and sanitizing. An exam table, a restroom fixture or a door handle in a medical practice needs disinfecting.
How to Check Your Cleaning Company
- Ask which disinfectant they use and ask for the label or product name. A company that can’t tell you doesn’t know.
- Ask what the contact time is. They should answer without looking it up.
- Ask how they make sure surfaces stay wet for that time on a busy night. The honest answer is a working order: apply to a set of surfaces, move on, and come back to wipe.
- Ask how cloths and mop heads are kept separate between restrooms and clinical rooms. Color coding by zone is the standard approach.
Disinfectant Contact Time: Common Questions
Is dwell time the same as contact time?
Yes. Dwell time, wet time and contact time all mean how long the product has to stay wet on the surface to do what the label says.
Do disinfecting wipes have contact times?
Yes, printed on the canister. The same rule applies: the surface has to stay visibly wet for that long, which can mean using more than one wipe on a large surface.
What if the label says ten minutes?
Then the surface has to stay wet for ten minutes. In a busy practice, choose a product with a shorter contact time for the organisms you need to cover, rather than cutting the time on a slower one.
Can I rinse or wipe the product off afterward?
Only after the contact time has passed, and only if the label calls for it. Some products need a rinse on food contact surfaces.
How We Do It
Our crews use EPA-registered disinfectants suited to healthcare settings and leave them on for the full label contact time, working through rooms in an order that lets each surface stay wet before it’s wiped. Equipment is color-coded by zone, and product labels are available for your compliance file. See medical office cleaning and how often a medical office should be cleaned, or call 855-833-7665. More in all our cleaning guides.