Black tank: "septic" or "holding?"

[Taranwanderer]

So I've read a good bit on these forums, and I've talked to some of my friends who've been RVing for a while, and everyone seems to have a different answer to this question: do you consider your black tank a septic tank, where actual waste breakdown (aerobic, anaerobic, etc) happens, or do you just consider it a holding tank to be dumped and cleaned out ASAP? If it is indeed a septic tank, then there's things you don't want to put down there (bleach, etc) but if it's just for holding and flushing, bleach is a good way to clean and sanitize to keep odors out...so what's the general consensus? Are we trying to promote bacterial action, or are we just holding, dumping, and cleaning? Thoughts...?

[Twisty]

It is a holding tank.
Nothing more, nothing less.
Says so in the literature and manual. There is a tank flush fitting for use when you EMPTY, yes EMPTY the tank.

[Hoo Dad]

Anyone that tells you that the black tank is a septic tank, either aerobic or anaerobic, has been misinformed. The black tank is only a holding tank.

[miatared]

Holding tank.

From a wiki site:

...A septic tank is a buried, watertight container typically
made of concrete, fiberglass, or polyethylene. It holds the
wastewater long enough to allow solids to settle out (forming
sludge) and oil and grease to fl oat to the surface (as
scum) It also allows partial decomposition of the solid
materials. Compartments and a T-shaped outlet in the
septic tank prevent the sludge and scum from leaving the tank and traveling
into the drainfield area.....

[Triguy]

Definitely just a holding tank.

[Taranwanderer]

That was kind of what I was thinking as well. I don't think I really want any kind of septic action taking place down there, I think I want it emptied ASAP and flushed with a bleach-based cleaner to keep any nasties at bay. Unless anyone thinks a mild bleach solution would be harmful for flushing? (Pardon the pun!)

[Twisty]

I won't be using bleach in mine. Not all RV dumps go into waste water treatment facilities. If you dump bleach solution into a septic system it will get screwed up and not work.

[Mountainmanbob]

Originally Posted by Taranwanderer

do you consider your black tank a septic tank...?

no
most Septic Tanks
except some used in the desert sand
have leach lines
hard dragging those THINGS behind an RV
Mountainman

[hankpac]

The confusion arrises when comparing home based systems and RV models. A home based system as described above is meant to be an end use, that is by using a leach field water is re-absorbed into the ground and solids are digested. Hence the need for very water soluble paper, and no other products down the chute.
However the RV tanks are finite in volume. they MUST be emptied, wether or not any solid matter digestion occurs. While waiting until at least 2/3 full, depending on how long that takes, some bacterial action does indeed occur. This is SEPTIC activity. Bacteria are digesting the solid material (feces) and turning the entire contents into a slurry.
This is desirable, since you don't want solids sitting on the bottom of your tank ossifying, or against the valve solidifying and blocking the valve.
After draining, run the flush system, or use a hand-held wand in the hopper, and spray the tank out thoroughly, and if you wish, bleach it.
However I understand bleach, like ammonia and formaldehyde can harm the rubber seals on the valve. I am not sure about that, it is something I have heard. Bleach after a certain period becomes water and salt, and gases off the chlorine, and other volatiles, so it is marketed as relatively harmless to the environment. While still bleach it halts bacterial activity so using it while the tank is still full can shut down the septic action.

[dimurrrw]

Originally Posted by Taranwanderer

That was kind of what I was thinking as well. I don't think I really want any kind of septic action taking place down there, I think I want it emptied ASAP and flushed with a bleach-based cleaner to keep any nasties at bay. Unless anyone thinks a mild bleach solution would be harmful for flushing? (Pardon the pun!)

I have read that bleach can cause the valve seals to deteriorate.

[Herk7769]

Holding tank.

I do use RV-Digest-It a "septic like" product on a full tank of water at end of season to do a thorough "digestion" of any remaining black matter for 72 hours before I do the final flush and sanitization as part of my winterization process.

Otherwise a capful of Calgon water softener and a capful of laundry detergent at every flush.

[Mountainmanbob]

RV Waste Management
As distasteful as some might proclaim waste management to be, waste systems on RVs are a necessity. Actually, the relative simplicity of waste systems usually means not many problems actually arise as long as a little preventive maintenance and astute practices are employed. As with any major system within the coach, a certain amount of knowledge and attention at varying intervals will keep the unpleasantness to a minimum. Let’s begin with this article about waste management. See if you concur. Be sure to click on all the internal links! I’ve provided some interesting side trips to help you grasp the entire context of proper waste management.
It’s one thing to understand all the factors involved with RV waste plumbing systems. And quite another to be able to correctly dump those tanks periodically. Yes, there is a method to the madness! Check out these step-by-step procedures as recommended by waste management and RV industry experts. And do remember to clean up after yourself when using a public dump station. Most RVers understand this, but yet I still find campgrounds with deplorable dump stations. Please be courteous to everyone!