Throw a gallon of vinegar in the fresh water tank just partially filled with water so its not so diluted and then turn on all the hot faucets and let your fresh water pump pump it in until you smell the vinegar at the faucet then shut them off and let it sit overnight.
Since you drained the water tank to repair I'm assuming you haven't run water and it is still empty.
So Just make sure NOT to turn your hot water heater on because the tank is empty and you'll burn it up. How water heater does not need to be on to run vinegar cleanse thru.
I use one of these when I want to put antifreeze and/or vinegar into my fresh tank. Has a screen in it and hose extends to what ever length you need to get it into your fresh water inlet.
![](https://images-na.ssl-images-amazon.com/images/I/61TyMrDcOvL._AC_UL130_.jpg)
I do a vinegar cleanse often to keep all the water lines clean and help remove the minerals I pick up from CG well waters.