Doing the Dishes

Proper hygiene is essential to avoiding infectious diarrhea in the outdoors. The most important two activities are proper hand washing (or wiping with disinfectant gel or cream) and disinfection of drinking water. After these come a number of important actions, such as "food rules" (proper washing, cooking, and serving; what foods to avoid), bathroom hygiene, not sharing items like towels and toothbrushes, etc.

One important topic is how best to wash dishes in order to remove diarrhea-causing bacteria and viruses. A recent study published in the journal Wilderness and Environmental Medicine sheds some light on current techniques and offers a recommendation for an effective dishwashing method that can be employed during a camping trip or other expedition.

The author, Joanna Hargreaves, evaluated 18 three-bowl washing-up systems that are commonly used on expeditions or during travel to remote places. Each bowl contained 5 liters (approximately 5 quarts) of water; the variation was what (if anything) was added to the water, and in what order the dishes were washed and rinsed through the three-bowl series. The systems were tested by mixing the bacteria Escherichia coli into porridge in order to simulate contaminated food residue, adding a standard amount of the bacteria-laden porridge to the dishes, then washing and rinsing the dishes. The most effective washing-up system in this laboratory evaluation was removal of most food residue with detergent (5 milliliters or 1 teaspoon) in the water in bowl 1, followed by a finishing wash (scrub until clean) with bleach (10 milliliters or 2 teaspoons of 4% chlorine bleach) in the water in bowl 2, followed by a final rinse in drinkable water in bowl 3. The final rinse was felt to remove the taste of the detergent and bleach (the latter considered to be a disinfectant).

The author made a few final recommendations, including using hot water in bowl 1, using a scouring pad or brush in bowl 2 with the bleach in order to avoid contamination of the scourer, allowing all utensils to air dry after washing, and cleaning the washing-up bowls and allowing them to dry between uses. Another suggestion is to use up to 100 milliliters or 20 teaspoons (3 teaspoons = 1 tablespoon) of bleach in bowl 2 if there is a current outbreak of diarrhea and vomiting. This increases the disinfection power of the second bowl.

Remember, these recommendations are based on an experiment, and can't take into account variables such as more severe contamination, different infectious organisms, how vigorously the dishes have been washed, etc. However, the concentration of bacteria used in this study to contaminate the porridge probably exceeded any that would be found in real life, so the advice offered from this study makes a great deal of sense.

Tags: hygiene, dishwashing, diarrhea, wilderness medicine, outdoor medicine, healthline

photo by Paul Auerbach

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