what you do is to not worry about it too much.
It is a good idea to use a potable rated hose for your fresh water supply and only your fresh water supply.
Have a separate hose for cleaning and other purposes.
Having color coded hoses can help you keep them separate.
When filling your fresh water tank, always allow the hose to flush by running water through it for a bit before connecting it to your system or filling your tank.
There isn't anything really harmful, such as lead, in any modern garden hose. If you flush the hose first, you probably won't even notice any taste. Of course, if you are in California or are paranoid about such things, you probably also have a bottle of dilute hypochlorite to spray down the faucet before you connect the hose and take a bunch of other precautions ;-)
Letting your supply hose sit in the warm sun with full water pressure is a good way to see if you can leach out any odd tasting 'chemicals' - put the pressure regulator at the faucet end and try to keep the hose out of the sun if you can.