Since I cannot actually look at your RV's water heater there is no way for me to tell what actual damage has been caused by the freezing. Just because it holds water does not actually guarantee that it can be used safely.
The fact that you see visible cracks means that there was definitely damage; so I would strongly recommend not to attempt to turn it on until you have it thoroughly inspected by a Certified RV Technician and hopefully it will not have to be replaced.
You might want to have the rest of your RV's plumbing inspected as there could be damage to some water lines in hidden areas that could be leaking and causing water damage in your RV.
Once your RV plumbing is inspected and repaired you are going to have to make sure that you winterize your RV every winter to prevent similar damage. Winterizing is not as complicated as it sounds, but when properly done it can prevent hundreds of dollars of damage to your RV's water system. It basically involves using RV Antifreeze to keep the water in your RV from freezing and bursting pipes. If
your RV does not have a built in water heater bypass system, it is recommended that you install a Water Heater Bypass Kit that allows you to drain and bypass your water heater and keep it from freezing and bursting. Installing the actual bypass kit is simple and straight forward (see the video below). The hardest part of the installation is getting access to the rear of your water heater.
We have a great article on our website called Winterizing Your Motorhome that verbally walks you through the winterizing process. One thing you need to realize is that winterizing your RV involves a lot more than the water system.
Sorry you are going through this and I hope that the above information has been helpful to you.
Do you have any suggestions or comments on this topic? You can add them to this page by clicking on the "Click Here To Post Comments" link located near the bottom of this page.
Everything-About-RVing.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.