Travels with ted
Turn the hot water heater off. Then, empty the fresh water tank.
In a bucket, mix ¼ cup of bleach and 1 gallon of water for every 15 gallons of tank capacity.
Use RV sanitize setting to pump cleaning solution into tank. Fill rest of tank with potable water.
Let cleaning solution sit in the tank for a minimum of 4 hours. It is fine to sit overnight.
Drain the tank. Then, fill with fresh water. Then, drain again. Repeat until you no longer smell bleach.