Black tank- dump it or leave it?

ralphnjoann wrote:

And again... water is your friend. You should NEVER leave the bottom of the tank dry... EVER. Dry black tanks, or insufficient water are what cause the dreaded pyramid.

Good advice for summer, maybe not so much for winter.

Water first fills your drain pipe. If exposed, and even if it's not,it can freeze in the winter and burst. Be sure and add some RV antifreeze. I could add, "Don't ask me how I know.", but I won't because I think it's overused to the point of being trite.:B

X2

Yup. Location, location, location. One size does not fit all! :W
Forum members from all over this United States from all different climates. Ya gotta sort thru them to see what fits where you live.

Black tanks WILL stank in Florida summers don't care if you think they are sealed your toilet opening is not.

Any Water left in lines in winters in Wisconsin WILL freeze.....
....and on and on and on.

It all depends where you are LOCATED as to what should be done for your RV. Amen.

And again... water is your friend. You should NEVER leave the bottom of the tank dry... EVER. Dry black tanks, or insufficient water are what cause the dreaded pyramid.

Good advice for summer, maybe not so much for winter. Water first fills your drain pipe. If exposed, and even if it's not,it can freeze in the winter and burst. Be sure and add some RV antifreeze. I could add, "Don't ask me how I know.", but I won't because I think it's overused to the point of being trite.:B

PawPaw_n_Gram wrote:
Letting a black tank sit does not generate odor in the rig if the vents are working properly. If there is plenty of water, solids do break down extensively.

As said many times - the key is plenty of water in the black tank at all times.

I would tend to agree with this. So long as your black tank vent works properly and your toilet drain seal works properly, you shouldn't have a problem. Leaving your toilet lid down will help reduce any evaporation issues. The longer your solids sit in water, the more water they absorb and the softer it becomes. Look at dog poop out in the rain... it absorbs water, expands and becomes very soft. That's why I try to clean out my dog's yard BEFORE it rains.

OP, if you want to go this route, I would throw one of those black tank chem packs down just before you leave. that will help break stuff down while you are gone.

And again... water is your friend. You should NEVER leave the bottom of the tank dry... EVER. Dry black tanks, or insufficient water are what cause the dreaded pyramid.

Then again, as long as you are properly draining and flushing out your black tank, there is no need for this and you should just drain your black tank before you leave and add a couple gallons of fresh water back in.

atomlinson wrote:
... I currently fill the black tank the rest of the way up to full or 3/4 full with the foot pedal, a garden hose,

Just have to share.
Reading your post brought back not so fond memories of garden hoses and/or me holding that pedal down on the toilet while water trickled out that small water inlet down the toilet drain to get some water into my empty black tank so I could add the chemicals too!!:B

Yup I think we've all been there done that in the beginning until we 'learned' about the bathroom sink draining into the black.

WHAT a difference. Dump your tank, turn around and open both faucets in the sink and done! Can even be done at the dump station it's so fast.

Do take a few minutes and test if your sink dumps into your black.

If you ever are camping where there are no hookups or you have to break camp to use the CG dump station?

Knowing about that sink dumping into your black you can adjust your families routine and have them brush their teeth and wash up in the 'kitchen' sink instead of the bathroom sink. Just changing THAT for me solo netted me 2 more days before I had to dump!!!

On June 20 we had an axle/hub failure while towing between two campgrounds. We had not dumped in the previous five days, and since the black tank wasn't full and we were going to a FHU campground - I didn't dump before departing.

The rig sat on the dealer lot while the extended warranty and ordering new axles and deliver and installation process took 31 days. This was 100 degree weather in the Dallas area. We had no problems with odor.

When I got the rig back, and a friend towed it to a COE FHU park - I dumped the tanks and flushed the black tank. It was the cleanest dump and quickest flush I've had in years. Filling the black tank after 8-10 minutes of flushing produced only clear water when I dumped it again.

Letting a black tank sit does not generate odor in the rig if the vents are working properly. If there is plenty of water, solids do break down extensively.

As said many times - the key is plenty of water in the black tank at all times.

Thanks everyone for the replies. My questioning has nothing to do with convenience/inconvenience of dumping the tanks, I was just merely curious that if I did in fact leave my black water in the tank for a while, maybe it would better break down the solids before dumping, without having a major odor problem in the process. I currently fill the black tank the rest of the way up to full or 3/4 full with the foot pedal, a garden hose, or with the black tank washout,on Sunday before we depart. Then immediately dump the tank, let the washout run for a while, then close the valves. I'll do a little experimenting and see what happens. Again, thanks everyone.

Fill with water, then dump it. No reason to keep **** fermenting in your RV if you don't have to.

rockhillmanor wrote:
Depending on WHERE you are located will depict how much it will smell.

And I am hear to tell you it will smell if you are parked in hot weather states. If you are lucky and the coach doesn't smell when you come back, when you go to use that toilet the first time I guarantee you you will smell it!

Absolutely True! We live that exact scenario. During the winter, I don't worry too much if I didn't dump the black, but during the summer's extreme desert heat!! Oh man, the stench could make a person pass out - or clear a campground if left to fester in the tank.

Lynnmor wrote:

rockhillmanor wrote:

Dump the tank, add chemicals, and run some water into the black tank from the bathroom sink which usually dumps into the black tank.

I agree with dumping the tank before leaving it. It serves no purpose to leave the stuff in there, for a week or more, when it could be mostly clean water.

The idea of using the sink to add water is not correct for many (most?)RV's, the sink may be connected to the gray tank.

Yup it IS correct for 'most' RV's!

To find out how your RV is plumbed:
All you have to do is dump both your black and gray tanks, close the valve and then go inside and run a good amount of water in the "bathroom" sink.

Then go out and open each tank valve separately to see where the water comes out. Most of you'all will be mildly surprised your bathroom sink dumps into the black!!

THE most common problem to the question:
"Why does my black tank fill up so fast?".....usually 2 adults 2+ kids ALL washing their hands and face, and ALL brushing their teeth with the faucet on like they do at home in the bathroom sink.
All the that water adding to your black tank. :C

AND

As Deb and Ed M stated above. If left parked long periods of time the water in the p-trap in the bathroom sink will evaporate and will allow sewage gas to enter your RV. The answer to the other question of why does my RV smell like sewage! :W

If your tank is hooked like our Class C was, with the lav sink also emptying into the black, odors can back up if the trap under the sink dries out. Just plug the sink, to be safe.