How to remove black water clog

[Johninar]

I had a blockage problem in my old Excursion. Tried a lot of things and finally did the rid-X thing. Came back a week later and it flushed out just fine. It does sound like you have a roof vent issue though.

[LK23]

Looked at the roof vent today. No obstructions.

[keymastr]

Well, you mentioned in your first post that you turn on the black tank flush for 20 seconds but that is not nearly enough. I would fill the tank overnight with fresh water and flush much more thoroughly in the future. Sitting overnight with clean water may soften the clog and help flush it out. If you have a clear elbow on your dump hose it allows you to see what is coming out. I fill and dump several times and even after 3 times it finds much more "stuff". I think you just have a buildup that is blocking the outlet, or your dump valve is not opening all the way.

[LK23]

Just to clarify, I dump when the black tank is at least 60 % full, then I use the black water flush to refill to at least 40% and dump again. Most times I do this again. I never finish until the clear fitting is showing clear water running from the black tank. After closing the black tank valve, I run the black water flush for at least 20 seconds to fill the sewer piping below the black tank. I do this with each dumping of the black water which is typically every three days. I have been using the procedure on two different motor homes while full-timing for the past 9 years and never a problem until now.

[FatChance]

Originally Posted by LK23

Looked at the roof vent today. No obstructions.

Did you take the cap off and look or probe down the vent to check for an obstruction in the vent?

[LK23]

No, I am not getting on the roof. Too old and bad back.

[Russtj60]

Have you tried a professional rv tank washing service? I have no experience but saw this link:
https://outsideourbubble.com/gray-an...sh-out-service

[robisinwa]

I'll share my experience, though I hope your not having a similar issue, just because sometimes in life your left scratching your head why people do what they do.

We would get intermittent clogging issues dumping the black tank, sometimes no problem, other times could tell the tank wasn't getting emptied (not enough flow and gauge said so). We tried switching to a lighter (thinner) brand toilet paper, tried leaning the coach to the drain side via the air bags when it would seem to happen, wouldn't happen for a bit, then wham, clogged again.

So finally got up in the drain pipe with a plumber's snake and could tell was hitting something. A bit messy to use a plumber's snake on a tank that isn't empty, but since I'm already in the do-do so to speak, I went all in and starting taking valves off, pulling elbows apart... to get straight to the do of it, someone had dropped an inch to inch and 1/2 and foot long stick down the toilet at some point.

We traced back a timeline from when the clogging first started happening to around the time we took our coach to a volunteer event and let other volunteer's use our bathroom instead of the porta pottys for the event that the general public used. Who the heck dumps a large stick in someone's toilet after they were nice enough to let them use it to begin with!!

Years later now we're still scratching our head to who the culprit was but now we're the "not nice, stuck up people that don't let others use our bathroom" at events we go to. I just don't get people sometimes.

May you not have a thick stick in your tank 'causing the issue but unfortunately don't completely rule it out either.

[PeterFTH]

When I had a clogged black tank I bought a snake and that did the trick. Just be ready for .... well, anything. Good luck.

[Buly]

My bet is also on something not organic. Piece of manufacturing scrap, large paper towel, etc. I have DS 4369 with two electric toilets and the other day had to unclog one of them. Plunger did the trick thank God
In our case nothing hard like pice of hard plastic or wood can not pass thru the masserator pump.
I’m afraid someone has to start disassembly from the dump valve up to the tank, until he finds out what is obstructing the flow.
Also you can buy in the marine stores a sign that tells toilet users not to put anything in the toilet that they have not eaten first (excluding toilet paper).
Good Luck.

[fleatools]

I will weigh in here. Open the black valve with stinky slinky hose connected. Get a 5 gallon bucket of water and flush down the toilet. Big volume short time might be the push you need, repeat as needed. Have someone watch with a clear fitting to see if it rushes out. Always leave at least five gallons to swish around while driving and while storing, it naturally softens things up. Second solution they are selling these endoscopes that connect to your cell phone or computer on Amazon for around 20-40 bucks, they have a light on the end of them with a camera, that may be the way to see your obstruction. Best of luck!

[tsnell23]

I've read more great reviews on Happy Campers than anything. Haven't tried it yet, but did order some. I've read a lot of bad reviews on Digest-it.

https://www.amazon.com/dp/B007S0LDME...748420_TE_item

[jimmoore13]

You need...

One of these:
https://smile.amazon.com/Valterra-De...2517186&sr=8-3

And one of these:
https://smile.amazon.com/Camco-Flexi...2517228&sr=8-3

Work them both, back and forth. If that doesn't clean out the tank and drain, then you DO need a camera - works with your smart phone as a monitor: https://smile.amazon.com/Compatible-...2517309&sr=8-5

DON'T USE CHEMICALS. Caustic chemicals are dangerous to handle on the output side, and if you have a "mechanical" problem, from a sock to a piece of plastic, in the drain, the chemicals won't dissolve it anyway. They work on fats and hair, etc. Anything that can get rid of those will get rid of your black tank and your dump drain.

BE CAUTIOUS around the toilet flush valve and treat it and the dump valve with "lube" when your done. https://smile.amazon.com/Thetford-Dr...s%2C210&sr=8-3

IMPORTANT POINT: If you are full-timers, I also presume you stay parked for extended periods. LACK OF MOVEMENT is a problem. In a typical application, a full RV black tank moves some distance prior to dumping. At minimum, you leave your site and toddle on over to the dump station. That movement causes relatively violent sloshing in the tank. This motion emulsifies the solids and they come out as more of a slurry than what goes down the toilet. If you're parked all the time, perhaps hooked to a dump port right on your site, your toilet doesn't have the amount of water in it that your home toilet uses to move solids down the line. You may well have a big pile of poo and tissue in the tank that is encroaching on the outlet. A little patience with the hand-held spray wand will break it down.

If you don't have full hookups, and you must use a dump station now and again, perhaps you are using a tote tank - https://smile.amazon.com/Barker-2784...2518353&sr=8-2 - ...again, your rig is not agitating the black tank.

Empty the tank. Turn off your water supply. Open the flush valve. Use a flashlight and your mirror to look at what's going on in the tank.

So, if you're parked most of the time and hooked to a sewer dump (or using a tote), you need to routinely flush with quite a bit more water, and without the agitation of movement on the road, you need to inspect (through the toilet flush valve) and clean somewhat regularly...say once a month...using the handheld wand. Meanwhile, the dump valve attachment with back-flow cleansing water will keep the pipe nice and clean.

There's a reason home toilets are not designed as RV toilets are. The solids can build up quickly in an RV toilet, and without the agitation of movement, that pile ain't goin' anywhere.

[pomara]

Most macerators have a very small propeller made of plastic to grind up everything and push it through an elbow that is difficult to put the tip of your little finger in. This is pretty easy to clog up especially if grease or oil from cooking or cleaning dishes go down the drain. Your hose probably has a 3/4 inch male threaded hose connection on the end. I used quick disconnects from Lowe’s or Home Depot and a female to female hose connector. Use a heavy dose of Dawn Dish Detergent squirting it into your macerator hose. Connect a water hose and back flush your macerator into your black water tank. Flush out and repeat if necessary. If you are old enough to know what a Kodak Moment is you better be sure that your black water gate valve is open so what you back flush goes into your black water tank instead of all over you and your plumbing connections!! This is very simple and works well. I used Charmin toilet paper and back flushed when things slowed down. Using hose quick disconnects makes this easy, fast and pretty sanitary. I used quick disconnects on all my hose connections. I used a short hose with black electrical tape on both ends to avoid confusing fresh water hose with a black water back flushing hose. Good luck.