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How to Clean a Germy Sponge

by | Jan 15, 2014 | Archives

What gets a sponge really clean?

Researchers from Good Housekeeping  conducted tests in conjunction with EMSL Analytical testing lab in Westmont, NJ, to find out. Consumers used sponges for a week in their kitchens, and the lab tainted others with three common pathogens: salmonella, E. coli, and pseudomonas. We tested six cleaning methods — the dishwasher, microwave, and washing machine; bleach, ammonia, and vinegar soaks — to see which removed the most bacteria.

And the Best Germ Killer Is…

The bleach solution killed 99.9 percent of the three bacteria strains from all our test sponges (scrub and regular cellulose), a benchmark based on the EPA’s requirement for sanitization of non-food-contact surfaces. Mix 3/4 cup of bleach in one gallon of water, and soak the sponge for five minutes. The microwave and the dishwasher were the next most effective, zapping 99.9 percent of germs from the home-used sponges and from the lab-treated scrub sponges. However, on the lab-treated cellulose sponges, microwaving just missed the mark for E. coli (99.83 percent reduced), and the dishwasher didn’t quite get all the salmonella or E. coli (99.88 and 99.86 percent reduced, respectively). Put a sponge into a regular dishwasher load, using the “heated dry” setting. In the microwave, saturate the sponge (we used 1/4 cup of water for scrub sponges and 1/2 cup for cellulose); heat on High for one minute (scrub) or two minutes (cellulose). Keep an eye on it. Clean sponges weekly, and toss shabby ones.

How Did the Others Do?

A five-minute soak in full-strength vinegar averaged 99.6 percent bacteria elimination; in full-strength ammonia, 97.0 percent. The washing machine proved least effective, killing on average 93.0 percent of bacteria.

The Cleaning Process:

  1. Begin by adding a few drops of anti-bacterial dish detergent to the hot water.
  2. Wash the sponge thoroughly by working the water through the sponge. This can be accomplished by squeezing the water through continually along with agitating it in the water.
  3. Rinse thoroughly with clean water.
  4. You can place your sponge in a bleach solution (1 tablespoon of bleach with 1 gallon of water) as well. This step is optional as the next step will also sanitize the sponge.
  5. Place the WET sponge in the microwave. You can place it in a dish of water, but it may not necessary.
  6. Microwave on high for 2 minutes. Monitor it carefully to watch for any signs of burning. If it appears to be burning the sponge, turn the microwave off immediately.
  7. When it is finished sterilizing in the microwave, let it set for a few minutes to cool off. It will be HOT!
  8. Remove it with a pair of tongs or oven mitts to protect your hands from burning.
  9. It is recommended that even with sterilizing, you should only use your sponge for a week or two before replacing.

Additional Tips and Ideas

  • Keep two sponges in your kitchen at all times, one for the counters and one for the dishes.
  • Sterilize your sponges after using them to clean up any dishes or work areas that contained raw meat.
  • Do not place any metal sponges or scrubbers in the microwave. Simply use the bleach solution to sanitize.
  • If odor is a problem, try spraying some vinegar on the sponge before microwaving


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January 2014