Winterizing - Black tank

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

dnr733

Active member
Joined
Aug 4, 2020
Posts
30
Location
Columbia, IL
I am hoping to keep this thread specific to winterizing of the black tank. I see many opinions across the great wide web lol.
So,
Do you leave any water in the black tank?
Do you add any antifreeze to the tank?
I see some leave valves open? Why leave them open if you have antifreeze in the tank?
If you leave valves open, would that not invite unwelcomed rodents over the winter?

Of course any other thoughts and suggestions are very welcome.

Dan
 

Rene T

Site Team
Joined
May 20, 2011
Posts
18,004
Location
Farmington NH
I can’t add water because it will freeze. I use to flush the tanks real good then leave the valves open. I would always put a cap on the end of my sewer pipe to keep critters out. My cap had a water hose connection so I would leave that on loosely in case any water found its way down to the cap. Iwould add pink stuff to all my traps and put 3” to 4” in the toilet to keep the seal moist
 

steveblonde

Well-known member
Joined
Jan 8, 2015
Posts
3,927
Location
calgary alberta
I dont leave the black tank open to me that would be silly i flush it well the last camping trip and dump some rv antifreeze in the bowl. Make sure its empty but if there is some water left in it from flushing it it wont hurt anything so long as its mimimal it can get to minus 30c here for weeks on end i also drain the rest of the lines winterize them and dump a little antifreeze in the p traps
 

dnr733

Active member
Joined
Aug 4, 2020
Posts
30
Location
Columbia, IL
I can’t add water because it will freeze. I use to flush the tanks real good then leave the valves open. I would always put a cap on the end of my sewer pipe to keep critters out. My cap had a water hose connection so I would leave that on loosely in case any water found its way down to the cap. Iwould add pink stuff to all my traps and put 3” to 4” in the toilet to keep the seal moist
Interesting. Valves open but cap closed? What is the actual benefit of leaving the valve open regardless of the cap?
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
74,396
Location
At our Silver Springs FL home
If you put in an antifreeze mix, it makes sense to me to leave the valve closed. I use the air blow-out method for water lines, so just drained tanks and had valves closed. The only antifreeze was in P-traps and the washing machine internal pump.

There is something to be said for leaving some liquid in the black tank and adding antifreeze to it: if there is any accumulated poo & paper that didn't flush out, it will dry rock hard over the winter. If you aren't confident the tank is well-flushed, leaving some water in it is maybe a wise precaution.
 

Viajeros

Well-known member
Joined
Apr 19, 2015
Posts
553
After we have winterized there is always some antifreeze that makes it into the grey and black tanks. We leave the valves open for a week or so but then close them so no critters get in. Works for us.
 

Rene T

Site Team
Joined
May 20, 2011
Posts
18,004
Location
Farmington NH
Yes it is always vented. When I said I didn’t want pressure on the seals I meant that with the gate valve closed, the seals would have pressure on them from the gate . With the gate opened there would be no pressure on the seals allowing them to sit in there natural state. It may not do anything but it’s just my way of thinking.
 

Kirk

Well-known member
Joined
Oct 30, 2005
Posts
782
Location
Full-time , Escapee
I have owned various RVs over the past 40+ years and in Wyoming, and later Texas. With the modern RV that has PEX and PVC plumbing, things are not as critical as they were back when water lines were copper as they will take freezing of a small amount of water but your pump will not. To stay with the black tank, a small amount of water in it will harm noting if it should freeze, but it is possible that the line to the dump valve could freeze and break. It isn't probable but it is possible and has occasionally happened in very cold climates. I have tried many different ways of doing things, with good success, but today I leave the black tank open and the toilet empty and drained. I haven't left the dump valves open but did for a long time and left the cap off as well to allow it to air our and dry. Since the sewer dump connection is suspended out in midair, I have never know of anything getting inside, but in recent years I have left the dump valves closed and the cap on.
 

Members online

Forum statistics

Threads
120,170
Posts
1,206,221
Members
125,219
Latest member
Mark from bc
Top Bottom