How you wash your utensils matters

When you’re out in the wild for extended periods of time, you’re always reminded of the need to eat. Some get around this by only carrying prepared foods. Others decide to cook, which inevitably leads to dirty dishes. Even if you make the grave sin of using disposable dishes and silverware, you still have to clean the larger containers you prepare the food in. And when somewhere between 1/3 and 3/4 of hikers end up with diarrhea, cleaning of these dishes is clearly important.

If you’re car camping and have running water, you can go ahead and move on to another blog post. Fresh running potable water makes this job easy. But for those times when it isn’t available, you need to clean your utensils somehow. Many of us have been taught the 3 bowl system seen above, where you wash in the first bowl, rinse in the second, and disinfect in the third. It has similarities to the 3 sink systems many restaurants use. But does this mean it’s best?

To find out, a group of authors decided to test 18(!) different 3 bowl systems to see which actually reduced bacterial loads the most. They used porridge contaminated with E. coli, a practice I can’t recommend when camping. (They describe the contamination in excruciating detail, using 232 words). The authors trimmed the systems to 10 after finding 8 of them “wholly inadequate.” Describing each of the systems is needlessly complex, so here’s Table 1 from the article.

This doesn’t entirely explain their methods though. When they wrote “established”, they meant washing until visibly clean in first bowl, then using 2 and 3 just for rinsing and sanitizing, as it were. “Alternative” meant removing all easy food residue in bowl 1, then getting them visibly clean in bowl 2, and rinsing in bowl 3.

Their results weren’t entirely surprising. First they note that grease is only removed with detergent. Second, while systems D, F, G, and J were best for bacterial loads, E through I were easiest to use because you could see what you were washing easier in the cleaner bowl 2, and D-I where the ones that didn’t leave a disinfectant smell on the dishes when done. Putting this all together, the winner was system G in using the least bleach while still reducing coliform counts below measurable levels.

Of note, systems B and C are often what is used and taught for wilderness trips. This may be due to a real or perceived need to decontaminate the rinsing water, but the authors recommend using potable water for bowl 3. Otherwise you are left with a distinct disinfectant residue on your dishes that can be tasted at your next meal. More importantly, due to reduced contact time with the disinfectant (dunking takes less time than cleaning), they had higher coliform counts as well.

So there you have it. You can use the 3 bowl system, but not the way it’s been taught historically. You should have water and detergent in the first bowl, cleaning them mostly. Then continue cleaning until visibly clean in a second bowl of water with 10mL of bleach in it (5L:10mL water:bleach). Finally, rinse in potable water. In severely water restricted circumstances,  this system gives you the added benefit of still working when you remove the 3rd bowl, except for that disinfectant taste again. The authors do note that if an outbreak of diarrhea occurs at your campsite, consider increasing the bleach content of bowl 2 to 100mL.

References

• Hargreaves JS. Laboratory evaluation of the 3-bowl system used for washing-up eating utensils in the field. Wilderness Environ Med. 2006 Summer;17(2):94-102. [PMID 16805145]