Is that water disinfected?

The question about whether or not the water in the RV tank is suitable for drinking shows up on the forums now and then, NASA faces the same problem with their RV, the space station. Water quality in orbit: Scientists test H2O disinfection on International Space Station at Physorg describes a new technique developed to test for proper levels of disinfectants in the water supply.

What NASA is trying to do is to avoid having to bring samples back to earth to test in much the same way that public water supplies are tested. It is one thing for a ranger to collect water samples from a campsite out in the boondocks and yet another for an astronaut to collect samples for testing in the lab back on earth.

“You can’t sterilize water well enough to keep things from growing in it,” Porter [University of Utah professor of chemistry and chemical engineering] says. “Nature happens.”

NASA uses iodine as a disinfectant on U.S. spacecraft. The Russians use colloidal silver – pure silver nanoparticles, some of which go into solution.

The problem for both iodine and silver is that microbes grow in the water if levels are too low. If levels are too high, iodine-treated water tastes bad and eventually might cause thyroid problems, and silver at excessive levels can turn the skin grayish blue.

Most RV’s and public water supplies use chlorine for both sanitizing and disinfecting. Those tend to dissipate over time which is good for well used supplies. Iodine tends to stick around so it is a good solution for longer term storage needs but does need care in getting the right dosage. Silver based disinfecting agents tend to be a bit more potent against “Cryptosporidum and Giardia, if utilized correctly” (wikipedia)

For the RV, if you sanitize the system before every season with a thorough fill with a solution of common bleach at a quarter cup to fifteen gallons to get a good smell, let sit overnight, then flush thoroughly, your tanks should be safe for drinking water. Flush and fill with fresh water from a public supply before each trip or at least weekly while traveling and the water should be safe to drink. If using a private well as a source, a disinfectant such as a few drops of common bleach, would be a good idea.

Perhaps this NASA technology will develop into a simple and inexpensive means that an RV enthusiast can use to make sure that the water in the holding tank has a proper level of disinfectant. That should ease a few minds worried about water safety.

See the CDC page Water Disinfection for Travelers by Howard D. Backer for a good summary of techniques.

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