RV How-Tos

Make Sure your Black/Sewer Tank Actually Empties

July 22, 2018

Nobody wants to deal with a black/sewer tank.  Even me.  What’s worse is dealing with a clogged tank or a sewer backup into your camper.  Maintaining a black tank is not difficult.  You just need to follow some simple steps.

Honestly, the main problem that I have seen with black/sewer tanks is that people don’t use enough water.  If there is not enough water in the black tank when you go to empty it there will not be enough force to get the solid waste out of the tank.  Simple as that.

Here are some other tips:

Only use RV toilet paper!

Never use Cottonelle, Charmin, etc.  Even the one-ply, cheap toilet paper is not a good idea.  The cotton content is so great that it will stick to everything, including your monitoring system and sewer tank sides.  I realize RV toilet paper is not the greatest.  It is thin, scratchy, and expensive but it is absolutely necessary.

Along these same lines:

  • No wet wipes.
  • No feminine products.
  • No diapers.
  • No rice (yup, I’ve seen it).

Use Chemical!

There are lots of different chemical brands on the market.  Use one!  If odors develop while flushing, you can add more chemical.  More chemical will NOT hurt your tank.

I recommend a couple gallons of water plus some chemical poured down your toilet into your sewer/black tank before you use your toilet at the start of the year.  Just plan to always keep a couple of gallons of fluid and some chemical in your sewer tank all season long.  This fluid will slosh around while you are traveling and it will help to break up the “ick” in your sewer tank and make it easier to empty later.

Emptying your tank at the dump station:

Before you empty your black tank, add some extra water by filling your toilet and then letting it flush down.  Do this a few times so you have enough water to create “the wave” and remove the solids from your sewer tank.

Next, remove your sewer cap (see above).  Often there is a little “juice” behind this cap.  I recommend wearing gloves.  If there is a lot of “juice” behind the sewer cap one of your valves may not be closing properly and may need to be replaced.  Next, attach your sewer hose and put the other end down  the dump station.  You may want to put a weight of some sort on the lose end of the hose as it may try to move when you open the valve and the fluids start to rush out.  Usually I just have my wife put a foot on it.

Now, OPEN THE BLACK TANK VALVE FIRST!  Just your black tank valve.  Not the grey tank, yet.  If you open all of the valves at once, solid waste and toilet paper can get up into the grey tank pipe and clog your grey tank valve making it so it won’t shut.  Some valves are easy to see handles and some are cables that are tucked under the camper or in a compartment.  The valves should be labeled.   When you first pull the valve, liquid will come out very fast.  Then it will slow down and look more like sludge (hopefully you will never actually see this).

The above photo shows cable gate valves (grey, black, galley).

If your camper is equipped with a “black tank flush”, now is the time you would use that.  The black tank flush is an input port on the side of the camper that you attach a garden hose to (it does have have a back flow devise so it is safe to use with a clean hose).  ONLY ADD WATER TO THE BLACK TANK FLUSH WHEN VALVE IS OPEN AND SEWER CAP IS OFF!  You can easily overflow your toilet or split your tank.  The black tank flush is used only to rinse your tank.  It does not have the pressure to knock a “cake” or layer loose from the bottom of your tank.

     

If your camper is not equipped with the black tank flush, you can achieve the same result by pouring water down your toilet with a 5 gallon bucket.  This method will help knock anything loose that is stuck to the bottom of your sewer tank.  It will also help to rinse out anything stuck in your sewer hose.

After flushing the tank, close the black valve.  Now, you can open your grey/galley valves.  They will also help rinse out anything stuck in your sewer hose.  I also like to use garden hose at the dump station when it is available to rinse out my sewer hose.

Important note!  NEVER attach the garden hose at the dump station to your fresh water input!  Some people put this hose in icky places (another good reason to wear gloves).

Some campers, mainly larger ones with two bathrooms, have two sewer connections.  Remember to empty both if necessary.

When your tanks are empty, (the hose will be light again) shut the grey/galley valves and reinstall the sewer cap.  Now, add 2-3 gallons of water down your toilet and add some chemical.  Again, this will slosh around while you are driving and loosen up anything stuck in your sewer tank.

If you have a sewer connection at your campsite:

Attach your sewer hose just as you would at the dump station.  There are some fancy accessories for this but we can discuss that later.  If you have two sewer connections you may need a Y-connection.  You can leave your grey/galley tank valve open while you are camping.  KEEP YOUR BLACK TANK VALVE CLOSED.  If you leave your black tank valve open, the fluid will drain out and the solid will sit there.  You now have an outhouse in your camper.  Ick!  Then, a couple of days before you leave, close your grey tank valve.  This will allow enough water to build up to help rinse your hose when you leave.  Then, follow the same instructions as above to empty your black tank.

Note: you don’t always have to empty your black tank.  The chemical in your tank and the sloshing while driving will work to break down the solids.  However, if you aren’t going to be using your camper for a week or more I would empty it.

Happy camping!!

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