Sinnettc...I sanitize our fresh water tank once in the spring in the de-winterizing process using
Camco FreshTabs. The process is MUCH easier (for me) and smells better afterwards than using bleach. So far, no problems...qualifier: we rarely "drink" from our fresh water tank (we carry gallon jugs of bottled water just because we prefer the taste) beyond sometimes rinsing our mouths after brushing teeth. We still wash our dishes with it and the dog seems fine with it too.
I'm not sure if geographic location might have anything to do with the development of bacteria in the "stored" tank (i.e. do warm year-round southern climes help create a more prolific growth environment?).
For the FreshTabs, I mix one tablet in a glass of warm water, pour it in the tank, add 15 gals of water, run pump water through all the pipes, drive trailer around the block, drain everything and flush once with 10 gals. of water.
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