How to Winterize w/ air compressor

Purchase (or go to Home Depot and get the parts to make your own) adapter for city water connection to your air compressor hose.
Adjust compressor regulator to ~45psi.
Drain and bypass water heater. If no bypass, then drain and install plug/anode.
Hook up compressor to adapter on trailer.
Work your way through the trailer, starting at your guess of the farthest away shower/faucet/sink/toilet/sprayer and run till no more water comes out.
Open low point drains and blow till no water.
Remove compressor, open all faucets.
Remove water heater drain/anode (if you didn't have a bypass) to drain newly acquired volume of water.

You can probably search the forum and find discussion on this. Here's how I used to do our travel trailer:

1. Drain the fresh water tank and water heater (also the black and gray tanks if you didn't do that when you brought it home last time).

2. Open all low point drains that you can find. My rigs have all had at least one on the cold side and at least one on the hot side. Open a cold and hot faucet while you do this so things will drain.

3. If your water pump were not broken, you would pump it dry at this point.

4. Set your air compressor to limit pressure to 15 - 20 PSI. Apply pressure to the city water inlet while you walk around inside and open the faucets one at a time until nothing but air comes out. This needs to be done for both the not and the cold sides.

My wife and I use our hand-held radios so one of us can hold the compressor hose on the flush nipple and the other can open and close faucets. Cell phones work, too, if you're in a place where you have a cell signal.

5. Finally, pour a little RV antifreeze in the sinks, tub drain, and toilet bowl to make sure residual water in P-traps and on top of the toilet valve doesn't freeze and do damage.

Rob

Get a RV Blow Out Plug to connect your air compressor to the city water inlet.

Thanks for all the advice!
What are the "low point" drains???

There are a couple of excellent responses to the question, so I will not repeat those good suggestions.

However, I would add two comments that were not mentioned and differ with one comment, i.e, blowing out the farthest water source first.

In my approach, I start with the highest water source which is the shower and end with the lowest which is the outside shower.

I open one valve at a time and place a paper towel in the shower, sink, toilet, etc. to verify that I got results.

The other point that didn't get mentioned is the toilet valve. You cannot get the water out unless the flush valve is open. I do not use another person to help, so I have a carefully measured 2x2 pole that rests against the kitchen cabinets when the flush valve is depressed. When done properly, it is not necessary to put RV anti-freeze in the fresh water system, which simplifies the un-winterizing process in the spring.

I have used this technique for 16 years with no adverse results.

ROADTREKKER2000 -Good suggestions should anyone decide to use the air blow.

I have been using RV Antifreeze and pump it into the water lines. With the right planning, I can do the job in less than 10 minutes and then I know that the water has been displaced by the pink antifreeze. Somehow it gives me a little satisfaction that nothing will crawl into the empty water lines. :)

Many people buy the Camco Blow-Out plug available at Wal-Mart -

The pumps are around $100, small price to pay to get the job done right and the guy you sell it to wont have the surprise of having to replace it.

And make sure you use an oiless compressor.

Thanks for the advice. Amazon delivered the blow-out plug and it's all done! We'll be selling it when we find a replacement, and will certainly tell all potential buyers that the water pump is broken.