Friday, June 9, 2023


Watch your dumping operation closely (but not TOO closely)

By Greg Illes
I don’t think anyone will argue that the dumping of holding tanks is the worst of RV jobs. This skanky task makes equals of us all: Young or old, rich or poor, we have to get rid of our sewage by dumping the black tank now and then.

Most folks have an understandable aversion to any close association with 30 or more gallons of waste disposal. But there are good reasons to brave the experience and “do it right.”

One inexpensive method is to install a clear fitting in your drain hose. Yeah, that’s right — so you can actually look at all that nasty stuff as it disappears into some septic system. Why, oh why, on this beautiful green Earth, would you ever want to do something like that? Well, there really are some pretty good reasons.

Ask yourself these questions about how well you’d like your sewer system to be working. The answers might suggest some corrective action to take before your system becomes inoperative.

• Did the effluent come out easily, or was it thick and slow flowing? (not enough water used)
• Did the effluent come out in a rush, or in a slow trickle? (blocked plumbing or tank)
• Is there undissolved toilet paper flowing by? (wrong paper used)
• After flushing, did the water run clear or still have contamination? (inadequate flush)

Hook up a clear fitting in-line with your drain hose and you can (however reluctantly) watch the process when dumping your black tank and assess the final condition of your tanks. A fitting can be placed at the beginning or end of the hose, but it’s easier to monitor progress near the RV instead of at the dump station port. Also, if you have room to semi-permanently install the clear fitting at your primary drain outlet, you can even check if one of your dump valves has been leaking (or left open) before you remove the cap and end up with a big puddle at your feet.

Camco makes a nice selection of clear fittings that connect to standard bayonet attachments and they come in various lengths, both straight and angled. You can buy one of these from Amazon or an RV parts store for $15-$20.

Additional reading:

Dumping RV tanks: Where do you go when you gotta go?
RV sewage dumping: Gloves or bare hands?

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his blog at



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John Koenig
2 years ago

Years ago, I read a tip re dumping an RV’s tanks that made a LOT of sense to me. Conventional wisdom has RVers dumping the black tank first, then the gray tank. The “improved method” was to dump just a little gray water first (5~10 seconds). In that short time VISUALLY CHECK FOR LEAKS! This way, IF there is a leak, you’ll be dealing with a gray water leak, NOT black water. Once you’ve confirmed there are NO leaks, close the gray valve, open the black valve. You’ll still have enough gray water left to purge the black water from your hose. Easy peasy!

2 years ago

You missed a great technique that I learned from my Country Coach owners manual. I added a valve at the dump outlet in addition to a clear sleeve. That valve becomes the “master” dump valve and stays closed except when dumping. Leaving it closed until I’ve hooked up the hose prevents any unsightly drips that may have leaked since the last dump. After dumping black, I close the master valve – leaving black open. Then I open grey, and let about half the grey water flow into the black tank. Then grey is closed, and the master opened again. This uses the relatively clean and soapy grey water to sluice out the black tank. Once it’s gone; black is closed, grey opened again and the hose gets cleaned out by the remaining grey water. This keeps my black tank clean and gives me total control of the dumping process. Highly recommend it!

2 years ago

Been using a 45 degree clear elbow at the RV connection for years and always watch the dump flow. Only once did I have any issue with the dump, and that was the DW’s overuse of TP. Seems the paper dammed the valve and blocked the discharge. Fortunately I had the tool to back flush the dam and unblock the valve. Highly recommend the clear fitting if you only occasionally glance at the discharge. The other benefit is knowing your tank is clear and clean when the rinse water runs clear (assuming you have a tank rinse system installed or available).

2 years ago

Explore the possibility of installing a Thetford Sanicon waste extraction system….no more stands, hoses to store almost zero effort to empty black and grey tanks

Jim Schrankel
2 years ago

I do two things before dumping my black water. Number one, is I use a sewer cap that has a hose outlet on it. I hold the slinky hose under the small cap and unscrew it. No huge surprises. Also, the common wisdom is to dump the gray water after the black water to clean the slinky hose. I dump gray water for a few seconds first, to make sure my connections are tight and the hose has no leaks.

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