I use a teaspoon of pool & spa chlorinating granules in the fresh water tank. Fill it, let it sit overnight, run it through all the faucets until drained.
Then I fill the tank again with just water. If I smell the chlorine, I may drain a second time and then refill.
My old TT had a horribly musty icky smell to the fresh water tank. Like a stagnant pool. I did the above twice and the water tasted just as good as from my home tap (which is the best tap water I've had). I did my RV when I first got it. I'll repeat if water sits for a long time and/or the taste changes.
