Winterization of Black Tank

ADRawli

I am heading into my second winter with our 2019 400, and just as I did last winter, have chosen the “blow-out with antifreeze in traps/tanks” method.  We live in Texas, where today it is almost 82F degrees, but in 2 weeks it could fall to 22F.  My question is that I realize I am unclear on what state to leave my black tank in this time around.  Hope this is an easy one.

Here is where I am at:  I have finished with draining of pump and tanks (fresh, black with rinse until clear, and grey), Alde, and low point drains.  I have blown out all lines, faucets/shower wands, and toilet inlet.  I feel pretty confident all (or nearly all) water is now out of the system and am ready to put antifreeze into the p-traps and grey/black tanks.  However, do I leave only the anti-freeze in the black tank, or do you all add some small amount of the Happy Camper chemical as well to ensure a sweet smelling system the next time out?  I worry that with only antifreeze in there the little nasty critters might take up shop during warmer weeks and surprise us with their fragrant activity when we open the trailer door the next trip out.  But, blending anti-freeze and HC might not be the best either, so just wondering what you all do when you prepare your toilet to sit alone over winter?  Is anti-freeze in there enough?  Thanks.

Sharon_is_SAM

I would drain the gray and black tank again after blowing out the lines, although there should be very little water in the tanks at that point.  We do not add Happy Camper over the winter, just AF.  Not sure if the HC enzymes are effective when mixed with AF and you need to dilute the HC with water, so it kind of defeats the purpose of the AF.  Make sure you get the AF on both sides of the tank valves.

VictoriaP

I’ll also add that simply rinsing the black tank until clear may not remove everything. Prior to winterizing, you should clean the tank as thoroughly as possible, using the onboard black tank flush, a spray stick down the toilet, or any other preferred method.

ADRawli

Good advice.  I think I’m clear on how to leave the black tank now, and confident that I’ve left it in a good, clean state, ready for any cold snaps that might come before we take it out again.  
Thanks!

PNWtabber

Sharon_is_SAM said:

I would drain the gray and black tank again after blowing out the lines, although there should be very little water in the tanks at that point.  We do not add Happy Camper over the winter, just AF.  Not sure if the HC enzymes are effective when mixed with AF and you need to dilute the HC with water, so it kind of defeats the purpose of the AF.  Make sure you get the AF on both sides of the tank valves.

Questions (my first time winterizing):

1. I'm not clear what is meant by: "Make sure you get the AF on both sides of the tank valves."  Can you help me out here?
2. Heading home from my latest outing (which was early October), I drained my gray and black tanks, and added Happy Camper and a couple of gallons of water to the black tank--I anticipated at least one more outing before winterizing.  Sadly, I didn't get out again before temps are now dropping.  With such a small amount of water in the black tank, I was hoping I could just go ahead and winterize (blow-out and AF in traps method) and add some precautionary AF to the black tank via the toilet?  I guess I need to read up on cleaning the black tank, hoping I can find a thread on that.
3. "I would drain the gray and black tank again after blowing out the lines, although there should be very little water in the tanks at that point." -- suggestions for draining tanks at home?  Designated bucket?  I'm not excited about hooking up and driving to the nearest RV dump and pay their fee if it is just a "very little water" in the tank.  

Thanks, as always!!!

Sharon_is_SAM

@PNWtabber - Plenty of AF down the toilet and drains moves AF to the “tank side” of the valve.  If you leave the sewer cap intact, then briefly open and close each tank valve, AF will then move towards the “outlet side” of the valves.  You end up with AF resting in the capped outlet section, thus imparting protection on each side of the valve.  Just make sure you leave the cap on😁

To drain the black tank at home, you can use a Blueboy portable tank, or even a bucket to empty into your house toilet.  Same thing with the gray tank.

qhumberd

So the area I cannot find an answer for concerning winterizing the black tank  is the black tank flush line. This line has an air gap valve to prevent backflow when flushing but I have not seen a recommendation to blow out this line when winterizing. I tried blowing out this line today after our final trip with some compressed air but really could not tell if there is residual water there or not. What do you all think? Is the backflow device at risk of freeze damage? The main hoses seem to be vertical garden hoses from the prior forum picture below (with sink removed).

The routing seems to come from the exterior then up to the backflow device (black valve in lower picture) and then back down into the black tank under the toilet. That sound correct?

Denny16

Blowing out the Black Tank Flush line with a compressor adapted to the inlet, should remove any significant amounts of water between the outside inlet and the valve, which has a low point that might collect water.  That said, he flush line is open on both sides of the check valve, and not likely to have any damage from minor amount of water left in it.

One could also push some antifreeze into the line for added protection.
cheers

qhumberd

Many thanks. May be overkill but that line is in a not very accessible spot if it were to get freeze damage.

Denny16

Yes the flush line is hard to access, best to be safe and get it drained, etc.
cheers