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How to Dump the Black Water Tank

As a new RVer, the number of things to learn about your new home can be overwhelming. Outdoorsy has created a new series entitled “One Big Question,” where we tackle one new action, walking you through what sometimes seems to be a daunting task. Today’s question is:

How can I dump the black water tank on my RV without getting grossed out?


This is probably the most asked question (in one form or another 😊) from new RV owners. And some of the answers can be rather humorous, if not a little ‘crappy.’ Just take a look at Liz Wilcox’s collection of “Tales From the Black Tank,” for some hilarious stories about black tank misadventures. Then come back to this article to discover how to avoid any dirty little mishaps, because dumping the tanks doesn’t have to be a dirty job, if done right.

List of Equipment Needed

  • Sewer hose with attachments (make sure hose has no holes in it)
  • Clear sewer hose elbow with an angle (45 or 90 degrees) for your particular system
  • Garden hose (not your freshwater hose)
  • Disposable gloves

Know Your Gate Valves

Your first mission, should you choose to accept it, is to identify the Gray Water and Black Water gate valves on your trailer or motorhome. Every RV has a different setup, but these valves will most likely be located close to where your freshwater is hooked up. Here’s what mine look like. I’ve labeled them so you can look for something comparable in your RV.

Photo Tripping America - Dump the Black Water Tank - Outdoorsy

In my motorhome, the black water tank pipe is larger than the gray water, but that is not always the case. Most are labeled and have a handle to pull the valve open and push it closed.

You’ll notice that the two valves are located close to where the plumbing for both tanks come together. There is a lid below the valves. This is where you will hook your sewer hose. Before you take that lid off MAKE SURE BOTH GATE VALVES ARE CLOSED! Then rotate the tank lid clockwise (off) and set the lid aside.

One other important note is to make sure your air vent in the bathroom is closed and turned off when dumping the tanks. Otherwise, you will be pulling some odors that aren’t too pleasant through the bathroom, and they won’t dissipate very quickly.

Gravity Always Wins

Because ‘crap’ flows downhill, make sure the sewer hose attachment site is uphill from where the sewer hose will dump its contents (at a dump station or septic tank).  Many RVers with full hook-ups (meaning they have electricity, water, and septic) at a campsite use a sewer hose support to create a downward slope to the sewer dump.

Attach a 45- or 90-degree clear sewer hose elbow to the “RV” end of your sewer hose, then hook the hose to the plumbing below the gate valves in your RV where the tank lid came off.  Once your hose is attached, put the other end in the dump station or septic hole at your campsite.  I would suggest placing a big rock on top of that end of the hose, so it cannot come out of the hole while dumping (this will help you to avoid any unhappy messes!).

Photo Tripping America - Dump the Black Water Tank - Outdoorsy

Let ‘Er Rip

Now you are ready for the action!  Open the black tank valve and let it completely empty through the hose into the sewer.  You’ll know it’s finished by looking at the clear elbow attachment (if you’re squeamish, don’t look until it sounds like the job is almost complete 😊)

When the blank tank is empty, close the black tank gate valve, then open the gray tank valve and let it empty, as well.  By emptying the black tank before the gray tank you are, in effect, helping to clean the sewer hose with the shower and dishwater stored in the gray tank.

Once both tanks are empty, close the gray tank gate valve, then you can do one of two things:

  1. If you have a clear elbow attachment with a sewer tank rinser (the hose attachment you see in the image above), then attach a garden hose to it (NOT your freshwater hose), open the black tank gate valve and turn on the hose to rinse the inside of the black tank. Close the valve when water runs out clean to the septic, open the gray tank gate valve and clean that tank, as well.  Here’s a great video to show you exactly how it works:

Then move on to #2:

  1. If you do not have a sewer tank rinser on your elbow attachment, or if you do and after you’ve completed #1, make sure both tank gate valves are closed, unhook the sewer hose from the RV, leaving the other end in the sewer hole at the dump station or campsite. Rinse the inside of the hose thoroughly with a garden hose (NOT a freshwater hose).

Clean Getaway

When your sewer hose is clean, collapse it and put it in a plastic trash bag or in your sewer hose storage compartment.  Put the tank lid securely back on the plumbing outlet in your RV, store your garden hose away from your fresh water hose, and wash your hands thoroughly.

There!  You’ve completed the dirty work without ending up like Robin Williams in the movie “RV!”  If you follow these directions, you’ll be able to ‘take care of business’ in about 5 minutes without ever messing with the ‘crappy’ side of life!  Now there’s absolutely no excuse not to rent an RV from Outdoorsy and explore more of the camping lifestyle.

Photo Tripping America - Dump the Black Water Tank - Outdoorsy

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