Anti-freeze in P-traps?


Active Member
Aug 14, 2012
I've read some people dump a little anti-freeze into sinks and showers to keep the p-traps from freezing up. I don't see why you'd do that. Shouldn't the water take the easier path and just expand up the open ends when freezing versus bursting the pipes? Also, where do you dump the anti-freeze the following spring when you flush out the system? I have septic and don't think I can dump it down my drains.

Does anybody use these instead of anti-freeze?


Aug 13, 2010
Lewisburg TN
I agree with theory on the p-trap. But not the antifreeze. The attachment to blow out your water lines only does the feeds to faucets not drains. I guess you might be able to wrap a rag around the fitting to create enough pressure to clear a sink drain, never thought about it.


Active Member
Aug 29, 2010
RV antifreeze is non toxic. Just let the drain run on the ground as you flush the lines out with water next spring. It won't hurt a thing. Probably wouldn't hurt the septic either but I'm not sure. Or catch it in a jug and take it to a dump station if you feel the need.


Running with the wolves
Nov 14, 2010
[SUN] I use the blow out and I also run a little antifreeze in my lines and drain. It can hurt. I would rather drain lines than have to replace broken lines.


Active Member
Aug 10, 2011
Hey BoomJammer. I use the threaded adapter for blowing out my lines as well. Make sure you can dial-down the pressure. I use my city water adapter pressure regulator.


May 17, 2012
Which threaded adapter do you use? The one from the link in my post (air hose connects directly to the adapter), or the one from the link in the OP (looks like a standard Schrader valve on the adapter)?

I do have a pressure regulator on my compressor output line. How far should I dial down the pressure? Probably to something under 50 psi, right?

Storm Trooper

Home is where you park it!
Feb 14, 2008
Where my camper is parked now.
If you live in an area that has serious freezes, use RV antifreeze.
For the few bucks it costs, it's not worth having water left over in the line do some damage.
Been there a long time ago.
The time and money it cost to fix the damage from freezing due to using air in the lines was not worth it.
If it costs $20 for RV antifreeze to run through each faucet and shower head, it's money well spent.


Active Member
Aug 10, 2011
Hey BoonJammer - I use the one you linked.

I dial the pressure down to about 40 PSI and combine that with my brass city water regulator. The adapter that Cullinan linked requires you to hold your pressure hose on all the time. Using the one you linked, I can have my pancake compressor supplying a constant amount of pressure while I can check the status of my lines and open all my taps.


Thanks Storm Trooper. I was thinking the same thing and failed to type it during my first post. I think I see that Cullinan is from Canada. If it were me, I'd probably leave my lines full. Down here in NC, it rarely gets down into the 20s so I'm good with just blowing out my lines after I run rv antifreeze through.


Woodbridge, VA
Jun 19, 2008
King George, VA
I put the antifreeze into the freshwater tank and pump it through until everything comes out pink at each faucet. I would rather spend the money on the anti-freeze than to have to fix everything. The guy I bought the van off of didn't winterize...I have spent close to $100 to fix his mistakes, and I still need a new toliet. It flushes now but still doesn't hold water due to a broken piece because of freezing... [2C]


May 17, 2012
Thanks for the winterizing tips! When I bought the camper last December, the previous owner told me he blew out the water lines. Being in GA and storing the camper in our garage, I didn't do any additional winterizing last year. But I'll probably experiment with the RV antifreeze and with blowing out the lines this year.


Super Active Member
Aug 23, 2009
I had a bunch of airline fittings (dad used to own a service station) so I just took a plastic blow out plug and drilled a hole in it and screwed a fitting in...a couple years later I found you could actually buy one ready made! If I lose or break mine i'll get one.

Screw it let's camp !


Week day camping is great
Jul 22, 2012
[TV] I used to ignore the p traps, then on one long campout the p trap under the sink and tub were both broken by freezing, everytime I used the sink the cabinet under the p trap was soaked and at the end of the season I discovered the floor around the tub was rotted out, That is one job I will never do again as now I use the pink antifreeze. When spring comes the 2 cups of antifreeze gets mixed with over 10 gallons of water and ends up in the dump station tank which is normally over 1500 gallons prior to being emptied out. The pink stuff will not harm the human body in small amounts. I never put it in my fresh water tank as I don't want to consume it, If anything, I put one cup of vinegar along with 5 gallons of water in my fresh water tank. then in the spring, I drive around to get the mixture sloshed around in the tank, then empty it and all is ready to go camping.