Heated city water hose

We are camping for Thanksgiving, it’s gonna get cold at night like in the 20’s so I bought a heated hose. Many on here are saying only use your fresh water tank and unhook the hose. Are they saying use the fresh water tank instead of buying a heated hose? If I’ve already got it which way is better? The coldest it will get is 20 on two nights and above freezing during the day. Thanks