Depends where your pipes and such run.
I have low drain points under the camper that have water in them regardless of tank or city source. They are below the belly cover. They will be the coldest.
Running water won't freeze, so if you let a faucet drip that should help.
Water expands as it freezes - it depends where it freezes whether you will have damage or hot - some ice in a holding tank should be an issue - it can expand upward.
In the flexible pipes I'd imagine it would be OK. In faucets, the pump and a full water heater tank I'm thinking you'd have issues.
Jill & Chris, Wills (14) Evie (11) & Toby our collie (5)
2011 Grey Wolf 28BH
2013 Chevy K1500 Crew w/ Reese StraitLine Dual Cam
Nights camped 2011: 11 2012: 18 2013: 12 2014: 12 2015: 13 2016: 3