Boiling water at 212° Fahrenheit (100° Celsius) for one minute kills germs and pathogens in the water, but washing with water that hot is unsafe for skin as it can cause severe burns. So how hot does it need to be to kill germs on surfaces and skin? Is there a safe temperature for hot water that will also sanitize?
Does Hot Water Kill Germs?
Boiling water kills the germs in the water, and it also can kill germs on surfaces of items submerged in the boiling water. Using moist heat is an excellent method of sterilization, which is why boiling baby bottles for five minutes is a recommended practice to sterilize the them. But when you're doing dishes, cleaning counters, and other large-scale projects, using boiling water isn't practical and could even result in burns and injuries. So if you're planning on hot water for sterilization for larger projects, it's probably not your best bet.
How Long to Boil Water to Kill Germs
If you have objects that you need to sanitize, boil them in hot water (if it's safe to do so) for one to five minutes. If you want to sterilize the water and make it safe to drink, the CDC recommends boiling it for one minute at elevations under 6,500 feet and for three minutes at elevations over 6,500 feet.
How Hot Should Water Be for Hand Washing?
If you're using soap and washing your hands properly, water temperature doesn't matter except for comfort. So, provided you're using proper hand washing technique, you can use hot water, warm water, cool water, or cold water and expect the same germ killing results. If you're using poor hand washing technique or relying solely on water without soap to kill germs, the water would have to be so hot and the contact so sustained, you would scald your hands. Therefore, choose a comfortable temperature for hand washing, study up on proper hand washing technique, and use a liquid hand soap or antibacterial soap to ensure your hands get clean.
Water Temperature to Sanitize Dishes
Is there a safe temperature for water that sanitizes dishes? It is unlikely you will be able to sanitize dishes when hand washing them using water temperatures that your hands can tolerate. Typically, you may be able to tolerate temperatures of about 115°F with your bare hands, and that won't cut it as far as sanitizing goes. To sanitize your dishes, try one of the following:
- After hand washing the dishes, if your dishwasher has a sanitizing cycle, run them through the dishwasher to sanitize them.
- Soak dishes for one minute in a solution of 1 gallon of water to 1 tablespoon of chlorine bleach. Water temperature doesn't matter.
- Soak dishes for 1 minute in water that is at least 170°F.
In both soaking methods, make sure the dishes are completely covered with water. Allow them to air dry naturally on a sanitized drying rack before putting them away.
Sanitizing Surfaces With Hot Water
Steam cleaning kills 99.9% of germs on surfaces on contact, making steam cleaners a safe and effective way to use hot water to clean and sanitize. Household steam cleaners are available for cleaning surfaces like countertops and toilets, as well as for cleaning floors and carpets. Some tips for safe and effective steam cleaning:
- Steam surfaces systematically so all parts of the surface come into contact with the steam. This is easiest to accomplish using a wide nozzle steamer and working in overlapping rows.
- Wipe away moisture from steam with paper towels and always wipe in the same direction so you don't reinfect the surfaces. Change paper towels frequently.
- Don't use sponges, which harbor bacteria.
- Always allow the steamer to cool and depressurize before opening the water receptacle and adding more water.
- Keep skin away from the steam as it comes out of the steamer.
Surfaces That Shouldn't Be Steam Cleaned
There are certain surfaces you shouldn't steam clean:
- Surfaces painted with water-based pain
- Porous surfaces
- Meltable plastics
- Raw wood
To sanitize such surfaces, a solution of water, bleach, and detergent is your best bet.
Hot Water for Sanitizing
Hot water is an effective sanitizer provided you have a safe way to use the water at the proper temperature. Dishwasher sanitizing cycles, soaking dishes in hot water to sanitize, boiling smaller objects, and using a steam cleaner are the most effective methods of using hot water to kill germs. For other cleaning projects, you're better off using a sanitizing household cleaner appropriate for the surface.