I used to use antifreeze, now I blow out the lines and fill the traps with anti freeze. Mind you I no longer have a fresh water tank nor a pump in my trailer so filling the lines with antifreeze is difficult.
I also use that $5 fitting from Camco to screw into the city water connection.
1990 Jayco 250 Special
2008 Ram 5500 DRW 6.7, Cummins, Aisin auto
Holland/Binkley 5th wheel, Reese Dual Cam, and more
232,500 kms in 2013
200,000 kms in 2014
160,000 kms in 2015