Winterizing Question

Hey all...I'm in need of some advice here. I gave the library a once over & didn't see anything about winterizing. To be honest, I'm in a hurry. I had planned to be living in my Rockwood already, but a change of plans at the last minute delayed that move & I had to put it back into storage until this spring. I've already drained the fresh water tank & all the lines as best I could. I know there is a small amount of water in the lines here & there, as well as a small amount in the tank...maybe a gallon, possibly two.

The black tank has a small amount of fluid left in it, as does the gray water tank & the galley tank.
I added treatment/chemical to all 3 waste tanks when I first put it in storage. I purchased 3 gallons of that pink nontoxic anti freeze yesterday at WalMart ($2.97 per gallon + tax) Sitting here now, writing this, I think I'll need another four gallons of the pink antifreeze. Three gallons for the fresh water tank & pump through the plumbing system. One gallon for each of the three waste tanks to mix in with any remaining waste water...can I mix the antifreeze with the chemical I added to the waste tanks?

The trailer is in Myrtle Beach, SC. It rarely gets so cold that I would be worried about solid-freezing of nearly empty tanks & plumbing.  What got me concerned, hence my post; The instructions on the jug of anti freeze say to drain the tanks completely & FILL 100% to the top with the antifreeze. WOW!

That's A LOT of antifreeze! That would be something like 100+ gallons. That's just crazy, IMO. I understand the need for this up north or wherever the temperatures drop below freezing for extended periods of time 24/7 and everything is frozen solid all winter. However, even with the current night temperatures reaching mid to lower 20's the day temps range between 50* and 65* It doesn't reach 32* and below until after dark, and as soon as the sky light up, the temps are climbing.

Any opinions?  Will a couple gallons of antifreeze in each tank  be sufficient in a situation like this? Other than the black water tank, the remaining fluid in the other tanks wouldn't be enough to dilute the antifreeze much at all...worse case scenario, it would be about 75% strength in the gray tanks, and about 85 to 90% strength in the fresh water tank. I just don't see the point in FILLING every tank to maximum capacity with antifreeze...not in this climate.

Do you not have a drain valve on the fresh water tank?  If not, then use your pump to run the tank empty, but don't let the water run into the gray tank if you can't drain that tank.  You can buy a switching valve that attaches to he fresh water line just ahead of the pump.  This valve allows you to suck water out of the antifreeze jug instead of the fresh water tank, which fills your lines with antifreeze.  My process is to drain the fresh water tank, drain all holding tanks, then flush lines with antifreeze until the pink liquid runs out of each faucet leaving the holding tank valves open while doing this.  Then, I close the valves and add 1/2 to 1 gallon of antifreeze to each holding tank thru the sink, shower drains and toilet.  I never use more than 3 gal of antifreeze and do not put any in my fresh water tank.

Don't add antifreeze to the holding tanks.  Just drain them and the little water that remains won't do any damage if it freezes.  Do either run antifreeze through all the water lines, put some in each drain trap, and you'll be fine.  Or blow out all the lines with compressed air and just put antifreeze in the traps.

I too think it takes A LOT of antifreeze to winterize the wet way.. Which is why I use Ned's second option, Air out the fresh lines (I found it helps to blow them out like 10 times, waiting a few minutes between blows, that 10 is a variable by the way,  you will figure out how many are needed easily enough) and just use pink in drains and toilets.

I had a dump station at the winter lot so water in the waste tanks was NOT an issue, I added like a pint of pink to them is all.

Thanks for the replies everyone. Based on the provided info, I'll just add the pink stuff to the freshwater tank, run the 12 volt pump until it comes out all the faucets & toilet. Then I'll pour some in the traps and be done with it. I'm charging the 12 volt battery right now, so I can open the slide & spend a few hours ALONE! It's amazing, when I go by to open the trailer & check everything, about once or twice a month, it's like a little slice of heaven.

I usually end up napping on the couch, or bed, so peaceful...I can't wait to start full timing!
THANKS! for the replies, all were very helpful.

Whatever method you choose, don't forget the outside shower (if you have one). I had to Get Smart about that the hard way.  :

For me up here in Central Idaho and see temps as low as -20 to -30*F. So what I do is drain the fresh water tank, water heater tank, and dump all 3 holding tanks (2 gray water and 1 sewage). Open up my low point drains allow as much to drain out. The I've got a custom made air compressor fitting to hydrant fitting. I hook up the compressed air at about 40-50 PSI and go around systematically from lo to hi blowing all lines out. This includes the outside shower. I continue the air blowing method till no water can be seen. Then using a shop vacuum with a custom wand I can reach up into the water heater and drain it out. Then reversing the shop vacuum to blow I can blow the sink traps dry. So now I grab the anti-freeze and pour about 1 ounce in the toilet to keep the seal moist. That it. Not other anti-freeze used or needed.

Reason I don't use much of the pink stuff is the fact I've seen it freeze solid in the tub drain and I was going to risk blowing a p-trap or a water line for some anti-freeze.

Something to keep in mind (since you're in SC) is that the plumbing is almost all plastic which is still somewhat flexible below freezing - and you won't see much of that.  Much more than copper or cast iron.  While you don't want to push your luck if it gets below 0 or so, just doing what others have advised you will work.  If you were living in your RV, just opening water faucets a tiny bit to allow a trickle flow will keep things from freezing even in that kind of weather.