Gard, But how am I suppose to get that warm fuzzy feeling when I see that nice pink liquid coming out all the orifaces of my trailer?  How do you know when the water has all been blown out?  Do you open one oriface at a time and wait till it stops spitting ?  How can you make sure you get all the water out of the holding tanks?  I would not mind saving the money on antifreeze but I need to make sure I do it right.

People can get warm fuzzy feeling from a multitude of reasons. If you do like pink colours, an air purge will be less than enjoyable.

The main difference is what you use to displace the water. The tanks and water heater are drained as usual and the heater by pass is opened. Air pressure is fed to the water inlet, and one by one, the faucets and toilet are opened, until only air escapes and no water flows from the fixtures. The drain to the potable water tank is opened, and any remaining water is removed. Then you add antifreeze to the sink and shower drains, and add extra to the toilet to treat any remaining water in the black holding tank, after their black and gray drains have been openend.

The damage done by freezing water is caused by the expansion of the liquid when it freezes. If the water is contained, the expansion will damage its surroundings. If there is only moisture left, its expansion is nominal and will not damage its containments. This is why a partially filled plastic bottle will not be damaged when it is frozen.

My warm fuzzy moment is when the job is quickly accomplished, with a minimal amount of time and costs.