RV antifreeze will evaporate if left open to the atmosphere. The cheaper version (and the only version I can find in stores the last few yrs) is the alcohol and propylene glycol mixture.
The alcohol evaporates off at a much faster rate when left open to the atmosphere (open system).
Propylene glycol also will evaporate when left open to the atmosphere (open system) but at a much slower rate.
In a closed system, evaporation will be minimal to none.
Your pressurized water lines if valves are closed are a closed system.
Your drain traps however are a "open system"" and over time both components will evaporate off.. Will not do any harm unless there is fresh water that was added to the traps.. To ensure traces of fresh water has been removed from the traps just add a fresh splash of RV antifreeze to top off the traps.
Water lines, if they were filled with antifreeze, there still should be antifreeze in the lines..
The downside to leaving antifreeze in the lines is the plastic will absorb trace amounts of the antifreeze making it difficult to clear the antifreeze taste.
