At the start of every season I link all of my white hoses together. pour in a 1/4 cup of bleach for every 5 gallons or so then with the free end of the hoses elevated slightly, fill the hoses until the water and bleach mixture fills the entire length. I let that sit for about an hour or so while I work on other pre season things.
I then connect the hose to the fill connection and fill the fresh water tank all the way to the top. I turn the water to the hose off and the on board water pump on, I run each faucet until I smell the bleach. This includes the washing machine, low point drains, fresh water tank drain, with the line to the ices maker valve disconnected, I run it until the bleach water comes out of the line a bit. Then I top off the fresh water tank and let it sit for about 3 hours.
After that it takes about three times of filling the tank and draining it to get rid of the smell which includes flushing all the faucets starting at the third fill.
It may sound like a lot of work but it's pretty simple. What you don't want is to get sick from bacteria living in the dark spots of your water system. I also replace the on board water filter at the beginning of each season so we have no issues at all drinking the water or using the ice in the ice maker.