I just use one of those X-Hose collapsable hoses. Packs up small and I don't have to worry that it's not drinking water safe.
But, to answer your original question, no, you don't HAVE to use a different hose. The actual chance of contamination is minimal. It's just highly recommended to eliminate even that minuscule chance.
There's no use crying over spilt milk... unless it's on your keyboard.