Most water carries microorganisms. When that water is held inside of a enclosed space (like a motorhome clean water tank) micro organism can multiply quickly. This gets to be even worse in warm temperatures. Legionella has become the most important worries, but so is E-coli and several other other sorts https://river0vgpy.vidublog.com/30226000/details-fiction-and-how-to-clean-and-sterilize-water-tanks-in-buraidah