Join Date: May 2005
Location: I live in a world of my own ( Worcs)
My Motorhome: Autocruise Starburst
That has happened to us on our previous van...I had cleaned the tank and pipes as normal but then a week or two later, a couple of outings later in fact, we had that same as you whiffy water. It turned out to be caused by algea ( green slime) that was caught in the convoluted filler pipe and that had been washed down into the tank when I used a particulaly high pressured fill ... it must have dislodged some of the crud that was stuck in the fill pipe and that went on to sour the whole tankfull... it was warm weather and that may have helped the bacteria get going..... so maybe check your fill pipe from the lockable opening down to the tank.
When confronted by a problem, you can solve it easily by reducing it to the question, "How would the Lone Ranger have handled this?"