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Ask Dr. Laundry

Ask Dr. Laundry

Disinfecting Water While Camping

By Dr. Laundry May 25, 2010

Q. My question concerns using Clorox bleach to disinfect shower and kitchen wastewater in a tent/camping situation. We don’t re-use the water, and we don’t expect 100% disinfection. However, we do need an easy-to-follow guideline that accommodates a variety of temperatures and quantity of contaminants, and will keep the microbes under control until we can dispose of the water. The rule of thumb I came up with was this:

For a gallon of wastewater, mix in a quarter cup of bleach. Let it stand for half an hour, then sniff it. If it doesn’t smell like bleach, add another quarter cup. Do this twice a day.

Am I grossly under- or over-dosing? Can you suggest a better rule?

A. Thanks for your interesting question. You didn’t say where the treated water was going to be disposed of. If it is back into a waterway, then we would want a little higher standard, but ground watering probably would have a little lower threshold.

Here are some quick calculations to get you grounded:


  • 1/4 cup Clorox® Regular-Bleach/gallon gray water would provide 900 ppm available Chlorine

  • For swimming pools, the range is usually 1-3ppm or 1/8 cup/100 gallons

  • For disinfecting potable drinking water in an emergency 1 tspn/gallon of clear water or 2 tspn/gallon of cloudy water; no chlorine smell after 30 minutes repeat until odor is present.


A difficult question to answer is how much organic load is in the water and how “uniform” is it from source-to-source and time-to-time. This has a direct bearing on your ultimate needed bleach level. So your suggested approach seems reasonable if you want to provide good quality water back into a waterway, since a noticeable chlorine odor would mean it is nearly “clean” water. If you are using the treated water for other purposes, then the single 1/4 cup application and stirring may be enough.