Thursday, March 03, 2005

Back to Nature - a blackwater tale

Warning! The following post is rated 'R'! 'R' for the Raunchy things you have to do when you live in a motorhome. That's right, I'm talking about the black-water tank. The holding tank for what goes into your toilet. There's a surprising number of lessons to be learned about handling the disposal of that black-water tank. Some you learn by reading and talking to other, helpful RVers ... some you just gotta learn by experience. I thought we had learned all there was to know after our year and a half of living in our motorhome. I was wrong.

For those of you who want to continue reading, don't worry, I didn't take any pictures. Before we ever bought our motorhome, Jim told me that his biggest nightmare was having to unclog the blackwater disposal system due to my excessive use of toilet paper. This revelation in turn caused me to have nightmares about living in a toilet paper-deficit state. We came to a compromise about this tissue-issue early on. First of all, we would only buy 'septic - safe' toilet paper. We learned that this doesn't have to mean buying expensive 'RV' paper from an RV supply store - Scott tissue from the grocery store is just as good.

Second of all, we would keep a garbage bag hanging next to the toilet so, if I felt the need for excessive tissue use, it would not be forbidden, I would just need to put it in the bag rather than the bowl. Whew! The very first night we stayed at an RV park the managers took us aside to be sure we understood the proper way to use the sewer hookup. I think we had 'new RVer' painted on our foreheads or something! You would think that being 'hooked up' means you can leave the line open so that waste gets disposed of immediately kinda like in a house. But, no! It just doesn't work that way.

Very little water is used in flushing an RV toilet - not like a house at all. Mostly, you just open the valve at the bottom of the bowl and let gravity take the contents of the bowl down to the holding tank, the water that is used is just to swish the bowl clean. So, if you had open pipes to the sewer hose, the solid waste would get stuck in the nooks and crannies, dry up and clog the whole system. You want the tank to be closed so the liquids and solids accumulate in the tank. And, make sure there are plenty of liquids - use more water than is really necessary for the 'swishing'. You also add a little bit of 'holding tank chemicals' to help break down the solids, dissolve the tissue, and keep down the smell. (make sure the chemicals do NOT include formaldehyde or chlorine bleach as these are bad for septic tank systems) Then, when the tank is nearly full, and the contents are all in at least a semi-liquid state, you open the valve on the outside of the motorhome, where the sewer hose is connected and let it flush into your sewer connection.

The last major lesson is that, when you 'dump' your blackwater tank, you want to dump the gray water (from the sink and the shower) immediately afterward, that helps clean the sewer hose. We must have learned those beginning lessons pretty good cuz, in our year and a half, we have had NO problems.

Till yesterday.

It's OK to leave your gray water tank open to the sewer hose because that is all liquid. We don't normally do that however, because we like to have the gray water to flush out the black water. But we had it open yesterday. So, when I smelled the need dump our blackwater I figured I was being real smart to only dump part of it. I wanted to close the gray water valve and take a shower so there was some gray water to rinse with after dumping the whole blackwater tank.


Once you open the blackwater valve, you want the entire contents to dump. The gravity and the pull of the dumping process is important, if you stop it part way it can (and did) get clogged up. Yuk. ummmm ... Jim? I need you to do something. Dick offered us some dynamite if needed ... 'just a quarter stick', he said. It took some time, but, luckily we didn't need to use dynamite, or hands, or even poking sticks. We have this 'cleaning wand' attachment that goes on the end of a hose and sprays water all around the sides. After spraying enough water in thru the top, and coaxing it all a little, the clog finally let go and we were back in working order without too much mess.

I hope my sad tale here helps some other RVer somewhere along the line. Pay attention to the books that come with your RV. Take classes like at Life on Wheels. Participate in the online forums with other RVers at And, always be prepared for a new 'experience'.

p.s. (added 3/8) A fellow RVer, John, reminded me that I forgot to mention one, very important, lesson. That is, before dumping the blackwater tank, you want to open the valve to the graywater for just a couple seconds. This will give you the opportunity to insure that the sewer hose is connected securely. If it is not secure, you don't want to discover that with discharging blackwater. No! You REALLY don't want to discover it that way.


Deb said...

Oh, thank you! My husband thanks you...and I thank you...way ahead of time.

Anonymous said...

I see an electric incinerating toilet advertised in the back of Mother Earth News. They make a model for RV's and it costs $1600. It's 15 amps, 120V. When something like this is available, why in the world would people futz with blackwater tanks?

Just asking.

Anonymous said...

I thank you from the bottome of my heart...and our septic tank:) We are very green in this motorhome business and have been having problems with our toilet clogging up. After reading your blog I now realize what we have been doing wrong. We made the mistake of assuming that we should just leave the black tank open since we are hooked up to sewer...OOPS. Thank you so much for posting this:)

Discreet said...

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Teresa McGurk said...

I'm a new RV-er and I thank you for the valuable information. Unfortunately, I decided to do the research AFTER the clog well, after it "came to my attention." But I will follow your guidelines with religious devotion from now on. Avidly. Religiously. Thank you!

Unknown said...

Wish I'd read this before, now :-)

Off we go to fill the tank. After emptying it the first time, I thought, "oh! if it had only been open it wouldn't have smelled so bad." Now, we are clogged. :-(!