Talk about black and gray tank

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When you ask in several forums and Facebook groups about the gray tank and black tank there will be a lot of different and sometimes conflicting answers. This led me to write up the way we handle our gray tank and black tank. I used the best tips and tricks from a lot of full-timers and YouTubers and combined them here. We did not change this for a long time because it just works!


How to
Top 10 Tips at the dump station
The Geo Method
Ice cubes in the blacktank?


1 Attach the sewer hose to the dump station hole and, if you can find something heavy put it on the elbow so the hose will not “jump”
(We use a photographer’s light stand sandbag for it, just look it up on Amazon $10 for 2 bags)
2 Go over to your RV and hold the end of the hose under your cap while you remove the cap. (Any seeping will get into the hose)
3 Next, hook up the hose to the RV
4 Before you pull the handle on the black tank,  open the gray tank valve for a few seconds and close it again then check if there are any leaks. When you have a leak and would have pulled the black tank without checking, you make a bigger mess let alone the stink!
5 When all is good pull the black tank valve open.
6 Flush the black tank and then close the black tank valve.
7 Next, open the gray tank valve, this will also flush everything that is left from the black tank out of the hose.
8 Optionally flush/rinse the sewer hose and close the grey tank valve. To flush the tank fill it up with the valve closed then open the valve to create a rush.
9 When done dumping/flushing carefully remove the hose from the RV, keeping the connection high enough so nothing will spill and empty the hose into the dump station.  *)
10 The next task is to add about 3 to 5 gallons of water to the black tank to create a good fluid base again and optionally add some Borax (See GEO METHOD video below)

*) In case you have separate or more dump connections adjust this procedure but keep in mind the order how to do things.


  1. Add some water to the bowl before you go.
  2. Leave the fan off while flushing 
  3. Try not to use more toilet paper than you really need.
  4. A gentleman has to sit down all the time to keep the room clean.
  5. Do not flush anything besides toilet paper and human waste.
  6. Always have some water in the tank
  7. Check the roof vent on a regular basis
  8. Check out the GEO method at the bottom of this post.


Just to make it clear, the black tank is waste from your toilet, the gray tank is from your shower(s) and sink(s).

IMPORTANT; Keep the black tank closed

The reason to leave the black tank closed is so that the solids stay in the liquid of the tanks to dissolve and stay soft. If you have the valve open all the time, the liquid will be drained into the sewer and the solids will pile up and create the dreaded “poop pyramid”.

IMPORTANT; Keep the gray tank closed or create a P-trap

You also want the grey tank closed or sewer flies and other critters can come into your RV and/or odors from the (neighbors) sewer. Or the sewer may backup because of heavy rain and “burps” some stinky air in your RV. An alternative to keeping it open is to create a p-trap as in the picture.

Gray tank sewer p-trap

Dump when the tanks are 3/4 or totally full (You don’t have to dump both tanks at the same time)

Put on latex or other disposable gloves (to avoid any contamination) and get the sewer hose out. Before removing the cap to the holding tank drain opening, ensure both the gray and black water valves are both closed.

Avoid dumping tanks that are not at least 2/3’s full. If you have to dump, add water to the tanks till they become at least 2/3 full. This will help promote all the solids and particles to become suspended in the water and flow out of the tank. If you are going to travel before dumping, you can add some dish-washer detergent (1/4 cup to a tank) and let it slosh around. Caution: Too much soap may cause excessive foaming! (The ice cube trick as promoted on various media does not work, there is a YouTube video that proofs hat)

Attach the hose to the dump station hole first! It is a good idea to use a clear elbow and a hose ring to connect the sewer hose to the dump station hole, as this will hold the hose in place and avoid any splatter. If the ring or the elbow is not available, insert the end of the sewer hose into the dump station’s hole about eight to twelve inches (if you only insert the hose a few inches the hose may come out when dumping the tanks and that will cause a large mess). Use the hole’s cover, a brick, or something heavy enough to hold the sewer hose in place so it doesn’t pop out of the hole (Do not use an object that is small enough that it could fall into the hole and plug the dump station).

It is also a good idea to attach a clear plastic ring at the dump valve, so you know that when you flush the black tank it is clean.

Saddlebags for light stands 2 for $10 on Amazon to keep the hose in the dum hole!

Clear elbow on your tank valve (There are various angles available)

This part goes into the dump station hole.

This is called an RV sewer donut, it goes over the end of the elbow and then (at the smaller part)into the dump hole. Some campgrounds require this to seal off the dump hole against escaping gasses and also preventing contamination into the system.

Find them at

Map Of RV Dump Stations. Find A Dump Station Near You

Here at RV Dump Sites we strive to make finding a place to empty your tanks as easy as possible. We provide a map based search engine that let’s you see RV sanitation dump stations surrounding the area of your choice with just the click of a mouse. We also allow feedback from other dump station users in the form of ratings and reviews.

This is a platform for sharing dump stations you have discovered. We are community driven, and while we will be adding many dump stations, we hope that you will add some of your own as well. By sharing information freely, we can all spend less time researching. You can submit reviews about the dump sites and can rate other people’s reviews of the RV dump.

Join us today and find the nearest dump stations!



Did you know about the GEO METHOD to get a clean not stinky tank?

A quick note…You should use Borax… I keep calling it boraxo because my Grandfather ran a Chevron Service Station and I used to hang out there as a kid. One of my jobs was cleaning the bathrooms and filling the old Boraxo powdered hand soap dispensers. I just can’t stop calling it boraxo…
What about dumping ice cubes in the black tank to clean it? (Does it work?)
At one point or another, we’ve all heard the advice to add ice cubes to the RV black tank to scrub it out. In the clear black tank, I add simulated waste, and some ice cubes and go for a drive. Does it work? Check out the video to see!

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