Make sure the water pipes in your RV are not "copper" but plastic ! Copper pipes burst in sub-zero temperature. Diesel does not freeze; the water moisture in the diesel does !
@siu-hung Hung Thank you for the information. I drove diesel to Wyoming in winter and had to use anti-freezing liquid in the diesel to prevent diesel from freezing. So, you are absolutely right.. The copper water pipes broke one winter and my plumber advised me to use plastic pipes which are flexible and may not break like copper.