I follow the procedure in my Lance mannual
1 Drain water system
2 Prepare a chlorine solution with 1 gallon of water and 1/4 cup of household bleach
3 Pour 1 gallon of solution for each 15 gallons of tank capacity
4 Fill tank with fresh water
5 Open each faucet and water heater relief valve until water flows evenly
6 Set pump switch to off
7 Allow solution to stand for 3 hours
8 Drain and flush with fresh water.
9 To remove any chlorine taste or oder ,fill tsnk 1 quart vinegar to 5 gallons of water . Allow solution to remain in tank for several days if possible.
10 Drain and flush with fresh water.
I flush twice at the end. No taste other than clean tasting not stale water. Once a year ,every spring.