Might be able to see residual pink antifreeze in the sinks or shower. Pull the drain plug on the water heater. Should be empty. If you can see the fresh water tank, it should be empty. If you have low point drains they might be open or if not, open them to see that there is no water present.
2006 Gulf Stream Friendship G7
350 Cat, Crusier Lift w/ Honda VTX
Blue Ox and 2019 Chevy Blazer RS AWD V6