Black Water Tank Plugged

[Lndeatr]

Hoping someone can give me some suggestions on unplugging the black tank.

Our last trip was in January. We went from Northern CA to Texas and back, about 2 weeks. Our gauge for the black tank has never been accurate and the last dump it said it was 2/3rds but not much came out. I figured it was empty and the gauge was off.

Well we used it over the weekend for a volunteer event (Relay For Life) at our fairgrounds and I added sanitizer and hooked up the hose to the flush fitting/in-tank sprinkler to add water to get it ready. Normally I hear it spinning and spraying. This time, no spinning and it kinda had a gurgling sound. When I got to the fairgrounds I dumped and only liquid came out. I would estimate 10 gallons. When I tried to flush with the hose via the fitting I could hear the water going in but very little came out at a trickle. I confirmed the right valve was open. If I add water and let it sit for about 5 minutes, the water comes out pretty quickly and then stops. When I add more water while dumping, it only trickles out.

Correctly me if I'm wrong but this tells me there is solids that are blocking the valve after I open it, and when I add water it takes a while to get through the blockage and to the valve. At this point I have no idea how much is in there and how big the solid blockage is. It is obviously full enough or big enough to stop the in tank flush from spinning. I am hesitant to use a snake as I don't want to tangle it in the in-tank sprinkler/flush.

Any suggestions on something that will dissolve the waste that is in there?

Do they make an adapter to hook on the drain and backflush? Am I mat risk of pushing "bad stuff" up the toilet or out of the vent?

Any help would be gladly accepted.

Martin

 

[cfulton]

Had a 09 3055 that did like yours-------the cut out for the upper connection had dropped into the tank and blocked the outlet after a couple of "slow" dumps!
Service folk punched back into the tank then luckily it flushed out. The punchee was not a happy camper!!!!!!!!!!!
Cheers not

 

[danemayer]

Hi Martin,

Here's a link to a clear twist-on adapter with backflush connection. There's also an external gate valve that closes the outlet allowing the backflush water to back up into the black tank. The clear part is essential to knowing what's coming out of the sewer outlet, and how much.

Make sure the gray tank valves are closed and use a timer (I use one on my phone) to ensure you don't overfill the black tank. I would assume about 5 gallons/minute from the campground faucet. Start with maybe 3 minutes of backflush to force solids and paper away from the outlet in the tank. After a few rinse cycles, you might increase that to 6 minutes.

Assuming the problem is a build up of solids, you might have to repeatedly rinse and drain for 5 or more cycles. Eventually you should get fast running water coming out.

The exposure to making a mess is mainly if you overfill the tank. The water has to go somewhere. Use a timer and proceed cautiously.

Don't operate the toilet while going through this procedure. If there's pressure, flushing the toilet creates a large opening for pressure relief. Your spouse will not like the results.

Sometimes problems like this are caused by an imperfect seal on the black tank valve. The water leaks out slowly, leaving a buildup of solids on the tank floor. As they dry, it becomes more and more difficult to clean the tank. The leak can be caused by something as simple as closing the valve while there's some paper that hasn't flushed out all the way. The paper gets caught in the blade channel, preventing complete closure.

It's also possible that the valve could be leaky.

A workaround is to install a standalone external gate valve on the sewer outlet (in addition to the one built into the backflush adapter). If this is closed, any leakage is limited to the volume of the sewer pipe. Also, when you uncap the outlet to hook up your sewer hose, you won't get any dirty water running out until you open the gate valve. Here's a link.

These valves and adapters are usually also available at local RV dealer parts departments.

We have some owner-written user guides, including a Water Systems User Guide that you may find helpful. It includes a section on tank maintenance with detail on clearing stubborn blockages.

 

[Lndeatr]

It appears prior to the last time I drained it, the liquids drained but there were solids that didn't drain (maybe the cut out issue cfulton had...) and I thought it was dry. Well between Jan and now, in triple digit heat over the summer that "stuff" must have turned to concrete along the bottom. Now when I put "liquid" in from the toilet or water in from the on board flush fitting the water sits on top of the blockage and eventually seeps through. When I drain only the liquid under the blockage comes out (no solids). When I hook up the hose to flush the tank, it fills on top of the solids and I only get a trickle from what is seeping through the blockage.

This week I am going to add a bunch of water (to the bottom of the toilet) and the Geo method (Water Softener, Laundry Detergent, and Chlorine Bleach) and let it sit for a while. From all the posts I've found on the web from people trying to dissolve waste, this seems to be the most recommended. Once the solids have dissolved I will go through the flushing as danemayer outlined. Any other advice would be appreciated.

Here is the Geo method. https://sites.google.com/site/cbruni/

 

[olcoon]

If you do have a leaky valve you might get something like this. We've had leaky valves from day 1 on our rig, took it to the dealer several times before the warranty ran out, and it still isn't fixed. I bought one of those valves & installed at the end of the dump line, and I've still got the leak, but this stops getting the "good stuff" all over me when I take the cap off to dump the tanks.

 

[Lndeatr]

No leaky valve yet. Every RV I've owned eventually needed new valves though.

 

[NWILSON]

The Geo Method seems to do a very good job at keeping solids from adhering to the surfaces of the tank. If your problem is the amount of solids built up in the bottom, I think I would use one of the products designed to break down the solids. There are many tank treatment products, like Odorlos, that may be helpful in getting the blockage to clear. Perhaps a call to the manufacturer of one of those products may get you some suggestions on dosage and time to "soak" to expedite the process!
Please keep us posted on your progress!

 

[Lynn1130]

There are services that clean black and gray tanks. They have all of the equipment to do that without getting a poop bath. Considering that you may have a pile of solidified substance below the toilet I would strongly recommend having a professional do it. It is not that expensive especially considering what you are going to have to do yourself and the danger of a major spill. Call you RV repair service. You will probably find that they have a service that they use and can recommend.

BTW, I watched this being done and they use a camera to inspect the tank and then send the cleaning wand in to clean it out. They do need to be at a dump site as they hook up with a connection that allows the tank to drain while being able to send the camera and cleaning hose in a hole in the cleaning connection up to the tank.

 

[mikeandconnie]

My 09 Landmark clogged up one time. I ran a water hose down to the tank through the tolet and the vent. I was able to break it up by moving and pushing the hose around in the tank. It took a while but I was able to clean it and never had the problem again.

 

[MagnoliaTom]

You could try a product call RV Digest-it. I've used it for routine maintenance but they claim it will liquefy solids and clear blocked pipes. I bought mine at ace hardware for about $16. You need to use the whole bottle and fill up the tank with water and let it sit overnight. Would be worth a try

 

[Lndeatr]

Well I couldn't find any of the RV Digest-it but I did find Roebic RV and Marine Black Water Holding Tank Treatment (http://www.roebic.com/rv-marine-black-water-treatment.shtml). I filled the tank and poured the whole bottle in on Saturday. Judging by the amount of water that it took, it had about 1/2 tank of waste (solid and/or liquid). Going to give it until Saturday and then dump it and see what happens. Hopefully I don't have the issue of the cut out blocking the valve like cfulton had. We are headed to Phoenix in a couple week for NASCAR and although there are porta potties near us, it is always nice to have my own.

 

[Lndeatr]

All is well now. I pulled the rig to the fairgrounds and dumped the tank. The Roebic RV and Marine Black Water Holding Tank Treatment seemed to have done the trick. Although it was very dark, everything that came out was liquid and once empty, is showed empty on the gauge. I flushed it until it came out clear and now am good to go. If it happens again I am gonna check to see if the cut out is indeed in the tank.

Thanks for all the advice.