Thank-you for the responses.
Hedge, when you open the low point valves it drains all the water in the lines out including from the city water inlet, when you re-pressurize the water lines with antifreeze it fills that city water inlet line with antifreeze as well as all the other lines in the camper. If you do not have any type of low point drain then i would suggest using compressed air through the city water inlet and open the taps inside the camper to purge most of the water before starting with the antifreeze.
Rtz549 - You are correct but its the freezing that cracks the lines, i also live in a climate that doesnt see below -10deg Celsius. If i am camping often over the winter i actually skip antifreeze all together and just use compressed air to blow all the water out (have to dry-run pump though).
