I seldom put the MoHo to bed without a full tank, why, the MoHo is our emergency command center. Electricity, water, beds, some clothes, toilet, and shelter. Never had a problem. Our water has to meet federal standards because we borrowed(never to be repaid) money from the Feds for upgrading and now it has so much chlorine in it that smell when you open the faucet.
In my other life living in an enclosed environment, we had a couple hundred gallons of emergency water. It was battery class water and the tank was SS. We changed it once in 6 years.
It is amazing how long water will last in a closed system, it may develop a flat taste but generally it will be safe to drink if pure H2O or chlorinated after many years.