View Full Version : Waste Water Flush

06-01-2009, 10:49 AM
I went to flush my waste tank for the first time this year and got a big shock. I have only had my unit for one year, thus first year for winter storage. I did all the items required for winterizing and when first opened for this camping year had no problems, other than this. I connected the hose to the waste tank flush system and let it run with the waste tank valve closed as directed. I could hear water running, but did not know that the flush hose system within the unit had created some leaks. I noticed once water was flowing out of the unit onto the ground. It took me three hours to get all the water picked up within the unit, flood in some peoples eyes. I check the hose and found that this hose goes up into the inner walls and cannot put this hose out to check. I am at a loss to why this occurred at least until I can get the hose out to view. So, has anyone else had issues with this systerm?

Thanks Jim

06-01-2009, 02:06 PM
Hi Jim. I believe the waste valve has to be open,cause you will fill the tank up with the flush water. As far as the rest of you post I cant help.

06-01-2009, 02:26 PM
When you use the flush system, you do need to close the valve to let it clean the inside of the tank just not forever as it will fill up. It sounds like the flush hose has a problem,there has been several post about this and how they got to it. Do a search here on the forum and you should hopefully get the answer as to how to get to this. Some have said there's a check valve that goes bad. We haven't had this problem yet and knock on wood won't. Good luck!!!

06-01-2009, 06:28 PM
When you winterized last year did you blow air through the fitting. If there was any water left in it then it may have frozen and damaged the hose.

06-01-2009, 09:33 PM
From the similar thread on this item, the plumbing of the flush line up the wall where you can't get at it is to meet some RVIA plumbing code. Guaranteed to result in service visits, probably. Since it appears to be another common leaker (like the shower stalls), my suggestion is to not use it and instead hook a Drain King, or similar attachment at the sewer connection and backflush the drain and tank. Again, you can't turn it on and walk away, but at least there's no hidden plumbing prone to leaks.

On our last two outings, I've started using the "Geo Method" in the black tank. So far, I've only used the water softener and not added anything else. And the tank drains fast and there is no smell in the rig, even holding the toilet flush open.

06-01-2009, 10:32 PM
I had a very similar experience with my 2007 Cyclone the first time I used the flush system. Turns out the manufacturer had put several metal screws through the hose that feeds the flush system when attaching the walls. The dealer had to take the walls apart to replace the hose as it was screwed through by the metal screws and attached to the wall, thus no way to pull it out. Long time to fix, but was covered under warranty. Sure hope your issue is easier to resolve!
Best of luck!

06-02-2009, 06:57 AM
Just a thought here, I've read somewhere that bleach will cause problems with seals in the gates. Not me saying this just something I read. I do not know one way or the other,just passing it along.

06-02-2009, 07:50 AM
Just a thought here, I've read somewhere that bleach will cause problems with seals in the gates. Not me saying this just something I read. I do not know one way or the other,just passing it along.

In high enough concentrations left for too long I am sure it could, but diluted with the other ingredients plus a few gallons of water. We use ours on a very regular basis as I have it, I am going to use it. I refuse to own an RV and not use the "Luxuries" in it I paid for.

The typical laundry water softener is a valid point. I was talking with another chap over on the North Trail site and we were discussing the use of Glycerin but that is not an inexpensive product.

06-02-2009, 12:18 PM
The Geo Method article is very informative. Thanks. I am going to give it a try. There is nothing to lose and everything to gain.

Uncle Rog
06-02-2009, 12:41 PM
We also use the water softener and detergent method, for a couple of reasons.
They actually seem to do a better job than the chemical treatments and they smell better too. When the softner is not available Borax is a good substitute and is quite a bit more economical. We really only use the Calgon / White King because of the added scent.
Just another thought, when using the sani-flush feature really pay attention when you have the valve closed. The RV forums have countless stories of people who have either overflowed the toilet into their rig or completely blown out the holding tank. In either case it would be a "sticky" mess.....................

06-02-2009, 01:23 PM
Take heed to Uncle Rog's advice. Don't ask me how I know.


Uncle Rog
06-02-2009, 02:08 PM
Sorry to hear that Don............

On edit, I have come close twice, scary stuff!

Bobby A
06-02-2009, 02:50 PM
I guess I'm a little confused, I was always told to NEVER you the sani-flush with the black tank valve closed. I never have and never will, in fear of over flow as mentioned. Furthermore, I had the sani-flush on my previous unit and used it regularly. I would winterize the unit in the fall by draining the water and pumping RV antifreeze through the lines. I never had the sani flush line freeze up but I often wondered why. I was told at PDI that the sani flush line did NOT need to be winterized. So now on this new Big Horn, do you need to winterize the sani flush line or not ??? If so, How do you do it ?? Thanks

06-02-2009, 03:20 PM
I have a friend that has been fulltiming for about 9 years. He is an escapee and very highly respected for his opinions about RVing. If your intrested you might read about the Waste tank and sewer odors.



I follow his advise about what to do with the black tank. 1 never dump until the tank is 2/3 full or so. I don't put any chemicals in the tank. It works very well by it's self. Just use plenty of water when you deposit solids. Rinse the tank numberous times until you see clear water coming out of the tank drain. If you do not have a clear adapter between the hose and the trailer you should.

I use the flush built into the trailer all the time. I close the sewer valve and let the hose inside the tank spray around in the tank. I will do this about 3 maybe 4 times before I finish. About onec a month I take a long hose and go into the trailer toilet and fill the tank up until I see the water in the toilet rising. I go out and pull the black tank valve and drain the tank. I do this at least twice. I then go to the sink drain and fill the tank until water comes up into the sink. Then I drain the gray tank. I do this because if you do not have a screen on the sink drains you will get food fragments in the gray tank and they will cause a stink.

I never use bleach on a gray or black tank. I empty my fresh water tank about once a month or if I have filled up at a place that has well water.

One thing to think about. If you put chemicals in your tank and then dump at a campground that chemical will react to their septic system. Use the natural system. Use nothing. It will take care of it's self, just use plenty of water.


06-02-2009, 04:00 PM

Short Answer:
Winterize the black tank flush to eliminate risk. I winterize my black tank flusher. Why risk it. I use a blow-out plug (couple $ at CW). Connect an air hose to it for a few seconds. Done!

Longer Answer:
My sense is that you would be fine not winterizing it but here again, why risk it. The check valve is high mounted. So when you have the water connected to it, you are pushing water up a vertical water line, it passes through the check valve, then down another vertical line and to the sprayer in the tank. This is why when you disconnect the water supply, some water runs out the connection. That's the water column before the check valve. So what happens to the water on the other side of the check valve? My sense is that gravity and a small amount of head pressure forces it to drain into the black water tank. And this is why you may be fine by not winterizing it - if you're up for some risk.

That all said, I just added a screw-on check valve at the black tank flush connection in the UDC. No more water pushing out when I disconnect. Not, for sure, I will always NEED to winterize as I could crack the check valve on either end and maybe blow the line too.


Uncle Rog
06-02-2009, 04:50 PM
TXBobcat has a valid point about not using any thing in the tank at all. When a rig is in fulltime mode the system is always being used and water is readily available. For us recreational users who dry camp a lot and water is used sparingly the treated tank method is best, I think. I also think that if a rig is to be parked for a while the added scent of the soap or softener is better than the "scent" I have encountered a couple of times in the past.....................

06-02-2009, 07:16 PM
I found it does not do a great job at flushing out tank.
I went back to my old system from my other trailer.

1/2 inch pipe, valves, elbow and bushing.
Loads of pressure and can direct the stream of water. and twist it around to get all areas.

Bobby A
06-02-2009, 10:27 PM
Thanks for the clarification Jim, I will for sure blow out that line this year if I'm not in Sunny Florida for the winter. Like I said though, I had my SOB for 7 years and never winterized the sani flush(because the dealer said I did not have to ) and never had a problem with the line freezing up. I think your thery is correct in why it didn't. thanks again.