Hello from Colorful CO

You will find a lot of different people will winterize using different methods and formulas.  We just returned from a 2 week trip to RMNP as well as the Black Canyon of the Gunnison, Cotopaxi, and other great areas in the Rockies.  This is our destination every other year and we look forward to visiting again in 2019. 

I just winterized our 177 today.  I use compressed air (60 psi) always keep 1 line open and go through all 5 lines (4 from the 2 sinks and 1 from the toilet)  Takes about 1 minute to go through the process.  I then take 1 pint of pink rv antifreeze and pour it down the 2 sink and 1 shower trap.  As far as the 3 storage tanks are concerned, fresh water is drained out (leaving about 1 - 1.5 gallons in the bottom of the tank.  The black and gray water tanks are drained out as well but I use a concoction of the following in each to sweeten the smell inside the tanks over the winter months.  1 cup borax, 1/2 cup Pine Sol and 3 tablespoons of ammonia in a 1 gallon milk jug.  Add enough hot water to make 1/2 gallon of final solution.  Shake up until mixed and pour half down the toilet and the other half down one of the sinks to get into the gray water tank.  I then add a gallon of water to the black and gray tank. Been doing it this way since winter of 2012, no issues, and the tanks smell ok in the springtime when we get ready to go podding once again.  Temps in northern Michigan where we reside will get to -15 or more during the cold snap in January.  Lastly I pull out both our 12v deep cycle group 24 batteries and place on the cement floor in our unheated garage.  I will give each a 2 amp trickle charge, this will take about 1 day / battery to bring to full charge.  The following spring I will repeat this process again, usually around the end of March or the first week of April.  Works for us, the batteries are nearly 7 years old now and get used a lot as most of our camping is where no electricity is available as in our national parks.

Originally posted by StephenH I'm  a bit more paranoid. I use air at no more than 50 psi. Then I use the winterizing connection to pump RV antifreeze through the pump and plumbing (after isolating the hot water tank). I find that even after I have blown the system out with air, I usually see some clear water being expelled before the pink gets to the faucets and toilet valve. I finish by pouring some RV antifreeze into the traps. Because I use a biological treatment, I don't do as Jim does since I don't want to kill the bacterial culture that breaks down the solids. I use TankTechsRx or similar products, and the odors seem to be minimal. I also make sure there is some RV antifreeze in the toilet bowl to keep the seals from drying out.

+1

Thank you for all of the helpful advice. Bottom line is leave some A/F treated water in the tanks lines and traps and this makes total sense. Thanks all! I'm sure you probably haven't heard the end of me.

Southwest CO is "the bomb." I hope you haven't missed Mesa Verde and Black Canyon is a quiet gem. If you ever want to stray from your routine, I'm quite familiar with southern WY especially the Snowy Range and Platte Valley. The Snowys are like a mini RMNP but empty. Looks very uninteresting as you might cruise past Laramie on I-80. My escape from Front Range chaos.

Originally posted by jato  Lastly I pull out both our 12v deep cycle group 24 batteries and place on the cement floor in our unheated garage.  I will give each a 2 amp trickle charge, this will take about 1 day / battery to bring to full charge.

I don't know if it's an issue or not, but I have read in various places that it's not a good idea to store lead acid batteries on concrete; especially in a climate where it's below freezing temperature. Based on this, I never put the batteries directly on the concrete, but put a block of wood (like a piece of 2x6) under each battery under my workbench.