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Old 10-22-2013, 10:08 AM   #1
Join Date: Nov 2012
Location: North Ga.
Posts: 2
Black Water Tank won't drain sometimes/most of the time

Hello everyone, I have a 2005 Rockwood/Forest River camper, model 8314SS. I bought it a little over a year ago and continue to have issues with the black water tank draining. I've pressure washed from the inside and this works but you can't do that at the dump station at a campground. There has to be something causing it not to drain properly but I can't figure it out. Any ideas? It seems that the previous owners may have left it over the winter without dumping it but I've been able to flush it out but there is still something not right. When you pull the handle to drain it, it doesn't rush out quickly like the gray water. Instead it barely comes out like something is blocking it but I can't find anything.

HELP!!!!!!! I'm thinking about having a camper place remove the tank but that is very expensive.

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Old 10-22-2013, 10:30 AM   #2
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Join Date: Oct 2009
Location: South Eastern PA
Posts: 21,370
Prevention is best, but you are in a pickle now.

Do you have a lawn sewer vent or access to a dump station close to your house/storage area?

I suggest:

1) Dump and flush as best you can.
2) Add 1 FULL QUART of UNIQUE RV-DIGEST-IT or Ridex Septic Tank Treatment to the black tank.
5) Drain and flush as best you can
6) Repeat.

This has saved many folks in your situation. Let me know how it worked for you and then we can talk about how to prevent this in the future.

Discount Liquid Septic Tank Additive , 24 oz., Bottle - RID-X Cleaning Equipment in stock at


Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
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Old 10-22-2013, 10:38 AM   #3
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It sounds like you have a "poop pyramid" which usually happens when an owner leaves their black tank valve open on a full-hookup site. The liquids run out, but the poopies don't. They mound up and cause angst and woe.

It seems RV Digest It is what you need. There are some previous posts here on FRF:
Anyone use RV Digest IT???????

Unique RV Digest-It

(I need to not get distracted by work- Lou beat me to it!)
2012 Ram 3500 DRW/crew cab/long bed/4x4/4.10 gears pulling a 2017 Spartan 1245 by Prime Time
Checkout my site for RVing tips, tricks, and info | My family and I have fulltimed since June 2015
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Old 10-22-2013, 11:08 AM   #4
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Posts: 162
Another theory is that something was dropped into the toilet and blocked the water escape. A friend of mine broke a toilet brush off while cleaning down in the toilet. Hasn't caused a problem yet, but who knows what a child may have dropped in the toilet and flushed it?
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Old 10-22-2013, 11:09 AM   #5
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Join Date: Sep 2011
Location: Langley, BC
Posts: 583
Had this very same problem this past season. We would drain the tank, flush it with the built-in flusher, and the next day it would be full to the top again. When we looked down into the tank, all we could see was white and water rising up near floor level. It looked like it was white PVC down there with a bend in it. Tried sticks and a piece of hose to clear it out. Nothing worked including pumping it out. Even got the portable tank out once just before midnight and partially drained the black tank only to find that the tank was plugged again in the morning.

In desperation, we used liquid Drano which does not harm plastic or metal (ie, the sensors). That did the trick and it looked clean enough down there to eat off (if you could or wanted too ). There may be some other chemicals around that will work as or nearly as good.

It turned out that whoever glued up the pipe at the factory used waaay too much ABS glue and it was hanging down around the pipe like stalactites and there was puddles of glue on the tank bottom. This was trapping the TP in there and there was nothing that could move it out of the way. For the first time, we could see the tank flush head next to the pipe into the tank and for the first time, our black tank sensors read zero. Very exciting! Pulling the toilet and trimming off the excess glue was the fix for this. It's the last thing I would have thought of and took an entire camping season to figure out. It wasn't until we were at a cg for a week with no sewer hookups that the problem came to a head. We had the honey wagon pump the tank out 2 days in a row and we had to use the nearby toilet building most of the time. Not cool... Spend tens of thousands on an RV and you have to use the public restroom?

If you do decide to try the drano method, you MUST use the type that is septic safe and won't attack plastic or metal. Then NEVER drain it into an on-site septic system because it will destroy the disposal field by killing off the bacteria in it. This can cause an owner many thousands to fix so make sure you don't do it. Many cgs have on-site disposal systems so beware... Do this at home if on a municipal system or at a dump station somewhere on one. Put the Drano in before you leave the cg and let it slosh around on the way home.

If even this doesn't work, you *could* buy one of those cheap USB cameras that can be pushed down a pipe, to find out what it's like inside the tank. Can't recall what they're called exactly.

Another point is that although there are a number or "RV" TP brands out there, some of them do not disintegrate like they should. I did a test of several brands last year and one popular RV brand (Thetford IIRC) didn't disintegrate. Some ordinary households brands DO disintegrate like an RV type should. One Costco type does and there are others.

If your RV type TP doesn't disintegrate, it will aggravate your plugging-up problem. There does not seem to be any standard out there and anyone can call it "RV" TP. If the glue is the problem, if you pull the toilet out, you should replace the gasket even if it looks okay.

FWIW, we never could see the bottom of the black tank from day one. Never thought twice about that. In retrospect, I'm positive that the problem started with the delivery guy during transit from Indiana to the west coast. I'm guessing that they likely don't spend extra on the RV stuff. Then the dealer was lazy in not checking and cleaning the tank?
Gil & Deb & Dougal the Springer Spaniel
Langley, BC
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Old 10-22-2013, 11:27 AM   #6
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Posts: 361
I have a 2009 Rockwood 8306 SS that I have had same issues with the black tank since I bought it new. It would seem I could never get all the "material" out no matter what method I used. I took it back to where I bought it and they even dropped the tank, looked inside, and said nothing is wrong with it and for me to add more water prior to use and to use more water and less TP when I use.
I have tried the GEO method, added 10 gallons of water prior to use, flush with plenty of water, and even tried not putting any paper down. At dump I will flush tank with water at 2 or 3 times (that always makes me new friends) use a 45 deg clear elbow that I hook hose on to flush from outside. Before I leave dump, I put about 6 gallons of water and some ice down toilet and let it slosh around on trip home. At home I will fill tank and still get "material" out.
I feel your pain. I have had several other campers and never had this issue. I am wondering if is just a bad design from FR.
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Old 10-22-2013, 12:40 PM   #7
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x73 on the RV Digest. Waiting for another 2 bottles to arrive.
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Old 10-24-2013, 08:31 AM   #8
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I have heard the bag of ice method works well - but you need to be moving for it to work properly. After your CG dump, put some water in it, then dump a bag of ice down there. While on the road the hard ice will bash into the side effectively removing anything stuck there, when you arrive at your next destination the ice will have melted and "cleaned" the black tank - drain it, and you should be good to go! Haha, get it?
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Old 10-24-2013, 11:12 AM   #9
Join Date: Jun 2013
Posts: 50
Several years ago we had the same problem. Since it was under warranty, took in to dealer. He dropped tank and found that when they cut the hole for the toilet the cutout piece had dropped into the tank.

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